/*
** 2001 September 15
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.463 2008/08/04 03:51:24 danielk1977 Exp $
*/
#include "sqliteInt.h"
/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.
*/
static void clearSelect(sqlite3 *db, Select *p){
sqlite3ExprListDelete(db, p->pEList);
sqlite3SrcListDelete(db, p->pSrc);
sqlite3ExprDelete(db, p->pWhere);
sqlite3ExprListDelete(db, p->pGroupBy);
sqlite3ExprDelete(db, p->pHaving);
sqlite3ExprListDelete(db, p->pOrderBy);
sqlite3SelectDelete(db, p->pPrior);
sqlite3ExprDelete(db, p->pLimit);
sqlite3ExprDelete(db, p->pOffset);
}
/*
** Initialize a SelectDest structure.
*/
void sqlite3SelectDestInit(SelectDest *pDest, int eDest, int iParm){
pDest->eDest = eDest;
pDest->iParm = iParm;
pDest->affinity = 0;
pDest->iMem = 0;
pDest->nMem = 0;
}
/*
** Allocate a new Select structure and return a pointer to that
** structure.
*/
Select *sqlite3SelectNew(
Parse *pParse, /* Parsing context */
ExprList *pEList, /* which columns to include in the result */
SrcList *pSrc, /* the FROM clause -- which tables to scan */
Expr *pWhere, /* the WHERE clause */
ExprList *pGroupBy, /* the GROUP BY clause */
Expr *pHaving, /* the HAVING clause */
ExprList *pOrderBy, /* the ORDER BY clause */
int isDistinct, /* true if the DISTINCT keyword is present */
Expr *pLimit, /* LIMIT value. NULL means not used */
Expr *pOffset /* OFFSET value. NULL means no offset */
){
Select *pNew;
Select standin;
sqlite3 *db = pParse->db;
pNew = sqlite3DbMallocZero(db, sizeof(*pNew) );
assert( !pOffset || pLimit ); /* Can't have OFFSET without LIMIT. */
if( pNew==0 ){
pNew = &standin;
memset(pNew, 0, sizeof(*pNew));
}
if( pEList==0 ){
pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db,TK_ALL,0,0,0), 0);
}
pNew->pEList = pEList;
pNew->pSrc = pSrc;
pNew->pWhere = pWhere;
pNew->pGroupBy = pGroupBy;
pNew->pHaving = pHaving;
pNew->pOrderBy = pOrderBy;
pNew->isDistinct = isDistinct;
pNew->op = TK_SELECT;
assert( pOffset==0 || pLimit!=0 );
pNew->pLimit = pLimit;
pNew->pOffset = pOffset;
pNew->addrOpenEphm[0] = -1;
pNew->addrOpenEphm[1] = -1;
pNew->addrOpenEphm[2] = -1;
if( pNew==&standin) {
clearSelect(db, pNew);
pNew = 0;
}
return pNew;
}
/*
** Delete the given Select structure and all of its substructures.
*/
void sqlite3SelectDelete(sqlite3 *db, Select *p){
if( p ){
clearSelect(db, p);
sqlite3DbFree(db, p);
}
}
/*
** Given 1 to 3 identifiers preceeding the JOIN keyword, determine the
** type of join. Return an integer constant that expresses that type
** in terms of the following bit values:
**
** JT_INNER
** JT_CROSS
** JT_OUTER
** JT_NATURAL
** JT_LEFT
** JT_RIGHT
**
** A full outer join is the combination of JT_LEFT and JT_RIGHT.
**
** If an illegal or unsupported join type is seen, then still return
** a join type, but put an error in the pParse structure.
*/
int sqlite3JoinType(Parse *pParse, Token *pA, Token *pB, Token *pC){
int jointype = 0;
Token *apAll[3];
Token *p;
static const struct {
const char zKeyword[8];
u8 nChar;
u8 code;
} keywords[] = {
{ "natural", 7, JT_NATURAL },
{ "left", 4, JT_LEFT|JT_OUTER },
{ "right", 5, JT_RIGHT|JT_OUTER },
{ "full", 4, JT_LEFT|JT_RIGHT|JT_OUTER },
{ "outer", 5, JT_OUTER },
{ "inner", 5, JT_INNER },
{ "cross", 5, JT_INNER|JT_CROSS },
};
int i, j;
apAll[0] = pA;
apAll[1] = pB;
apAll[2] = pC;
for(i=0; i<3 && apAll[i]; i++){
p = apAll[i];
for(j=0; j<sizeof(keywords)/sizeof(keywords[0]); j++){
if( p->n==keywords[j].nChar
&& sqlite3StrNICmp((char*)p->z, keywords[j].zKeyword, p->n)==0 ){
jointype |= keywords[j].code;
break;
}
}
if( j>=sizeof(keywords)/sizeof(keywords[0]) ){
jointype |= JT_ERROR;
break;
}
}
if(
(jointype & (JT_INNER|JT_OUTER))==(JT_INNER|JT_OUTER) ||
(jointype & JT_ERROR)!=0
){
const char *zSp = " ";
assert( pB!=0 );
if( pC==0 ){ zSp++; }
sqlite3ErrorMsg(pParse, "unknown or unsupported join type: "
"%T %T%s%T", pA, pB, zSp, pC);
jointype = JT_INNER;
}else if( jointype & JT_RIGHT ){
sqlite3ErrorMsg(pParse,
"RIGHT and FULL OUTER JOINs are not currently supported");
jointype = JT_INNER;
}
return jointype;
}
/*
** Return the index of a column in a table. Return -1 if the column
** is not contained in the table.
*/
static int columnIndex(Table *pTab, const char *zCol){
int i;
for(i=0; i<pTab->nCol; i++){
if( sqlite3StrICmp(pTab->aCol[i].zName, zCol)==0 ) return i;
}
return -1;
}
/*
** Set the value of a token to a '\000'-terminated string.
*/
static void setToken(Token *p, const char *z){
p->z = (u8*)z;
p->n = z ? strlen(z) : 0;
p->dyn = 0;
}
/*
** Set the token to the double-quoted and escaped version of the string pointed
** to by z. For example;
**
** {a"bc} -> {"a""bc"}
*/
static void setQuotedToken(Parse *pParse, Token *p, const char *z){
/* Check if the string contains any " characters. If it does, then
** this function will malloc space to create a quoted version of
** the string in. Otherwise, save a call to sqlite3MPrintf() by
** just copying the pointer to the string.
*/
const char *z2 = z;
while( *z2 ){
if( *z2=='"' ) break;
z2++;
}
if( *z2 ){
/* String contains " characters - copy and quote the string. */
p->z = (u8 *)sqlite3MPrintf(pParse->db, "\"%w\"", z);
if( p->z ){
p->n = strlen((char *)p->z);
p->dyn = 1;
}
}else{
/* String contains no " characters - copy the pointer. */
p->z = (u8*)z;
p->n = (z2 - z);
p->dyn = 0;
}
}
/*
** Create an expression node for an identifier with the name of zName
*/
Expr *sqlite3CreateIdExpr(Parse *pParse, const char *zName){
Token dummy;
setToken(&dummy, zName);
return sqlite3PExpr(pParse, TK_ID, 0, 0, &dummy);
}
/*
** Add a term to the WHERE expression in *ppExpr that requires the
** zCol column to be equal in the two tables pTab1 and pTab2.
*/
static void addWhereTerm(
Parse *pParse, /* Parsing context */
const char *zCol, /* Name of the column */
const Table *pTab1, /* First table */
const char *zAlias1, /* Alias for first table. May be NULL */
const Table *pTab2, /* Second table */
const char *zAlias2, /* Alias for second table. May be NULL */
int iRightJoinTable, /* VDBE cursor for the right table */
Expr **ppExpr, /* Add the equality term to this expression */
int isOuterJoin /* True if dealing with an OUTER join */
){
Expr *pE1a, *pE1b, *pE1c;
Expr *pE2a, *pE2b, *pE2c;
Expr *pE;
pE1a = sqlite3CreateIdExpr(pParse, zCol);
pE2a = sqlite3CreateIdExpr(pParse, zCol);
if( zAlias1==0 ){
zAlias1 = pTab1->zName;
}
pE1b = sqlite3CreateIdExpr(pParse, zAlias1);
if( zAlias2==0 ){
zAlias2 = pTab2->zName;
}
pE2b = sqlite3CreateIdExpr(pParse, zAlias2);
pE1c = sqlite3PExpr(pParse, TK_DOT, pE1b, pE1a, 0);
pE2c = sqlite3PExpr(pParse, TK_DOT, pE2b, pE2a, 0);
pE = sqlite3PExpr(pParse, TK_EQ, pE1c, pE2c, 0);
if( pE && isOuterJoin ){
ExprSetProperty(pE, EP_FromJoin);
pE->iRightJoinTable = iRightJoinTable;
}
*ppExpr = sqlite3ExprAnd(pParse->db,*ppExpr, pE);
}
/*
** Set the EP_FromJoin property on all terms of the given expression.
** And set the Expr.iRightJoinTable to iTable for every term in the
** expression.
**
** The EP_FromJoin property is used on terms of an expression to tell
** the LEFT OUTER JOIN processing logic that this term is part of the
** join restriction specified in the ON or USING clause and not a part
** of the more general WHERE clause. These terms are moved over to the
** WHERE clause during join processing but we need to remember that they
** originated in the ON or USING clause.
**
** The Expr.iRightJoinTable tells the WHERE clause processing that the
** expression depends on table iRightJoinTable even if that table is not
** explicitly mentioned in the expression. That information is needed
** for cases like this:
**
** SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.b AND t1.x=5
**
** The where clause needs to defer the handling of the t1.x=5
** term until after the t2 loop of the join. In that way, a
** NULL t2 row will be inserted whenever t1.x!=5. If we do not
** defer the handling of t1.x=5, it will be processed immediately
** after the t1 loop and rows with t1.x!=5 will never appear in
** the output, which is incorrect.
*/
static void setJoinExpr(Expr *p, int iTable){
while( p ){
ExprSetProperty(p, EP_FromJoin);
p->iRightJoinTable = iTable;
setJoinExpr(p->pLeft, iTable);
p = p->pRight;
}
}
/*
** This routine processes the join information for a SELECT statement.
** ON and USING clauses are converted into extra terms of the WHERE clause.
** NATURAL joins also create extra WHERE clause terms.
**
** The terms of a FROM clause are contained in the Select.pSrc structure.
** The left most table is the first entry in Select.pSrc. The right-most
** table is the last entry. The join operator is held in the entry to
** the left. Thus entry 0 contains the join operator for the join between
** entries 0 and 1. Any ON or USING clauses associated with the join are
** also attached to the left entry.
**
** This routine returns the number of errors encountered.
*/
static int sqliteProcessJoin(Parse *pParse, Select *p){
SrcList *pSrc; /* All tables in the FROM clause */
int i, j; /* Loop counters */
struct SrcList_item *pLeft; /* Left table being joined */
struct SrcList_item *pRight; /* Right table being joined */
pSrc = p->pSrc;
pLeft = &pSrc->a[0];
pRight = &pLeft[1];
for(i=0; i<pSrc->nSrc-1; i++, pRight++, pLeft++){
Table *pLeftTab = pLeft->pTab;
Table *pRightTab = pRight->pTab;
int isOuter;
if( pLeftTab==0 || pRightTab==0 ) continue;
isOuter = (pRight->jointype & JT_OUTER)!=0;
/* When the NATURAL keyword is present, add WHERE clause terms for
** every column that the two tables have in common.
*/
if( pRight->jointype & JT_NATURAL ){
if( pRight->pOn || pRight->pUsing ){
sqlite3ErrorMsg(pParse, "a NATURAL join may not have "
"an ON or USING clause", 0);
return 1;
}
for(j=0; j<pLeftTab->nCol; j++){
char *zName = pLeftTab->aCol[j].zName;
if( columnIndex(pRightTab, zName)>=0 ){
addWhereTerm(pParse, zName, pLeftTab, pLeft->zAlias,
pRightTab, pRight->zAlias,
pRight->iCursor, &p->pWhere, isOuter);
}
}
}
/* Disallow both ON and USING clauses in the same join
*/
if( pRight->pOn && pRight->pUsing ){
sqlite3ErrorMsg(pParse, "cannot have both ON and USING "
"clauses in the same join");
return 1;
}
/* Add the ON clause to the end of the WHERE clause, connected by
** an AND operator.
*/
if( pRight->pOn ){
if( isOuter ) setJoinExpr(pRight->pOn, pRight->iCursor);
p->pWhere = sqlite3ExprAnd(pParse->db, p->pWhere, pRight->pOn);
pRight->pOn = 0;
}
/* Create extra terms on the WHERE clause for each column named
** in the USING clause. Example: If the two tables to be joined are
** A and B and the USING clause names X, Y, and Z, then add this
** to the WHERE clause: A.X=B.X AND A.Y=B.Y AND A.Z=B.Z
** Report an error if any column mentioned in the USING clause is
** not contained in both tables to be joined.
*/
if( pRight->pUsing ){
IdList *pList = pRight->pUsing;
for(j=0; j<pList->nId; j++){
char *zName = pList->a[j].zName;
if( columnIndex(pLeftTab, zName)<0 || columnIndex(pRightTab, zName)<0 ){
sqlite3ErrorMsg(pParse, "cannot join using column %s - column "
"not present in both tables", zName);
return 1;
}
addWhereTerm(pParse, zName, pLeftTab, pLeft->zAlias,
pRightTab, pRight->zAlias,
pRight->iCursor, &p->pWhere, isOuter);
}
}
}
return 0;
}
/*
** Insert code into "v" that will push the record on the top of the
** stack into the sorter.
*/
static void pushOntoSorter(
Parse *pParse, /* Parser context */
ExprList *pOrderBy, /* The ORDER BY clause */
Select *pSelect, /* The whole SELECT statement */
int regData /* Register holding data to be sorted */
){
Vdbe *v = pParse->pVdbe;
int nExpr = pOrderBy->nExpr;
int regBase = sqlite3GetTempRange(pParse, nExpr+2);
int regRecord = sqlite3GetTempReg(pParse);
sqlite3ExprCodeExprList(pParse, pOrderBy, regBase, 0);
sqlite3VdbeAddOp2(v, OP_Sequence, pOrderBy->iECursor, regBase+nExpr);
sqlite3ExprCodeMove(pParse, regData, regBase+nExpr+1, 1);
sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nExpr + 2, regRecord);
sqlite3VdbeAddOp2(v, OP_IdxInsert, pOrderBy->iECursor, regRecord);
sqlite3ReleaseTempReg(pParse, regRecord);
sqlite3ReleaseTempRange(pParse, regBase, nExpr+2);
if( pSelect->iLimit ){
int addr1, addr2;
int iLimit;
if( pSelect->iOffset ){
iLimit = pSelect->iOffset+1;
}else{
iLimit = pSelect->iLimit;
}
addr1 = sqlite3VdbeAddOp1(v, OP_IfZero, iLimit);
sqlite3VdbeAddOp2(v, OP_AddImm, iLimit, -1);
addr2 = sqlite3VdbeAddOp0(v, OP_Goto);
sqlite3VdbeJumpHere(v, addr1);
sqlite3VdbeAddOp1(v, OP_Last, pOrderBy->iECursor);
sqlite3VdbeAddOp1(v, OP_Delete, pOrderBy->iECursor);
sqlite3VdbeJumpHere(v, addr2);
pSelect->iLimit = 0;
}
}
/*
** Add code to implement the OFFSET
*/
static void codeOffset(
Vdbe *v, /* Generate code into this VM */
Select *p, /* The SELECT statement being coded */
int iContinue /* Jump here to skip the current record */
){
if( p->iOffset && iContinue!=0 ){
int addr;
sqlite3VdbeAddOp2(v, OP_AddImm, p->iOffset, -1);
addr = sqlite3VdbeAddOp1(v, OP_IfNeg, p->iOffset);
sqlite3VdbeAddOp2(v, OP_Goto, 0, iContinue);
VdbeComment((v, "skip OFFSET records"));
sqlite3VdbeJumpHere(v, addr);
}
}
/*
** Add code that will check to make sure the N registers starting at iMem
** form a distinct entry. iTab is a sorting index that holds previously
** seen combinations of the N values. A new entry is made in iTab
** if the current N values are new.
**
** A jump to addrRepeat is made and the N+1 values are popped from the
** stack if the top N elements are not distinct.
*/
static void codeDistinct(
Parse *pParse, /* Parsing and code generating context */
int iTab, /* A sorting index used to test for distinctness */
int addrRepeat, /* Jump to here if not distinct */
int N, /* Number of elements */
int iMem /* First element */
){
Vdbe *v;
int r1;
v = pParse->pVdbe;
r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, N, r1);
sqlite3VdbeAddOp3(v, OP_Found, iTab, addrRepeat, r1);
sqlite3VdbeAddOp2(v, OP_IdxInsert, iTab, r1);
sqlite3ReleaseTempReg(pParse, r1);
}
/*
** Generate an error message when a SELECT is used within a subexpression
** (example: "a IN (SELECT * FROM table)") but it has more than 1 result
** column. We do this in a subroutine because the error occurs in multiple
** places.
*/
static int checkForMultiColumnSelectError(
Parse *pParse, /* Parse context. */
SelectDest *pDest, /* Destination of SELECT results */
int nExpr /* Number of result columns returned by SELECT */
){
int eDest = pDest->eDest;
if( nExpr>1 && (eDest==SRT_Mem || eDest==SRT_Set) ){
sqlite3ErrorMsg(pParse, "only a single result allowed for "
"a SELECT that is part of an expression");
return 1;
}else{
return 0;
}
}
/*
** This routine generates the code for the inside of the inner loop
** of a SELECT.
**
** If srcTab and nColumn are both zero, then the pEList expressions
** are evaluated in order to get the data for this row. If nColumn>0
** then data is pulled from srcTab and pEList is used only to get the
** datatypes for each column.
*/
static void selectInnerLoop(
Parse *pParse, /* The parser context */
Select *p, /* The complete select statement being coded */
ExprList *pEList, /* List of values being extracted */
int srcTab, /* Pull data from this table */
int nColumn, /* Number of columns in the source table */
ExprList *pOrderBy, /* If not NULL, sort results using this key */
int distinct, /* If >=0, make sure results are distinct */
SelectDest *pDest, /* How to dispose of the results */
int iContinue, /* Jump here to continue with next row */
int iBreak /* Jump here to break out of the inner loop */
){
Vdbe *v = pParse->pVdbe;
int i;
int hasDistinct; /* True if the DISTINCT keyword is present */
int regResult; /* Start of memory holding result set */
int eDest = pDest->eDest; /* How to dispose of results */
int iParm = pDest->iParm; /* First argument to disposal method */
int nResultCol; /* Number of result columns */
if( v==0 ) return;
assert( pEList!=0 );
hasDistinct = distinct>=0;
if( pOrderBy==0 && !hasDistinct ){
codeOffset(v, p, iContinue);
}
/* Pull the requested columns.
*/
if( nColumn>0 ){
nResultCol = nColumn;
}else{
nResultCol = pEList->nExpr;
}
if( pDest->iMem==0 ){
pDest->iMem = pParse->nMem+1;
pDest->nMem = nResultCol;
pParse->nMem += nResultCol;
}else if( pDest->nMem!=nResultCol ){
/* This happens when two SELECTs of a compound SELECT have differing
** numbers of result columns. The error message will be generated by
** a higher-level routine. */
return;
}
regResult = pDest->iMem;
if( nColumn>0 ){
for(i=0; i<nColumn; i++){
sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
}
}else if( eDest!=SRT_Exists ){
/* If the destination is an EXISTS(...) expression, the actual
** values returned by the SELECT are not required.
*/
sqlite3ExprCodeExprList(pParse, pEList, regResult, eDest==SRT_Callback);
}
nColumn = nResultCol;
/* If the DISTINCT keyword was present on the SELECT statement
** and this row has been seen before, then do not make this row
** part of the result.
*/
if( hasDistinct ){
assert( pEList!=0 );
assert( pEList->nExpr==nColumn );
codeDistinct(pParse, distinct, iContinue, nColumn, regResult);
if( pOrderBy==0 ){
codeOffset(v, p, iContinue);
}
}
if( checkForMultiColumnSelectError(pParse, pDest, pEList->nExpr) ){
return;
}
switch( eDest ){
/* In this mode, write each query result to the key of the temporary
** table iParm.
*/
#ifndef SQLITE_OMIT_COMPOUND_SELECT
case SRT_Union: {
int r1;
r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
sqlite3ReleaseTempReg(pParse, r1);
break;
}
/* Construct a record from the query result, but instead of
** saving that record, use it as a key to delete elements from
** the temporary table iParm.
*/
case SRT_Except: {
sqlite3VdbeAddOp3(v, OP_IdxDelete, iParm, regResult, nColumn);
break;
}
#endif
/* Store the result as data using a unique key.
*/
case SRT_Table:
case SRT_EphemTab: {
int r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
if( pOrderBy ){
pushOntoSorter(pParse, pOrderBy, p, r1);
}else{
int r2 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, r2);
sqlite3VdbeAddOp3(v, OP_Insert, iParm, r1, r2);
sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
sqlite3ReleaseTempReg(pParse, r2);
}
sqlite3ReleaseTempReg(pParse, r1);
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
/* If we are creating a set for an "expr IN (SELECT ...)" construct,
** then there should be a single item on the stack. Write this
** item into the set table with bogus data.
*/
case SRT_Set: {
assert( nColumn==1 );
p->affinity = sqlite3CompareAffinity(pEList->a[0].pExpr, pDest->affinity);
if( pOrderBy ){
/* At first glance you would think we could optimize out the
** ORDER BY in this case since the order of entries in the set
** does not matter. But there might be a LIMIT clause, in which
** case the order does matter */
pushOntoSorter(pParse, pOrderBy, p, regResult);
}else{
int r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult, 1, r1, &p->affinity, 1);
sqlite3ExprCacheAffinityChange(pParse, regResult, 1);
sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
sqlite3ReleaseTempReg(pParse, r1);
}
break;
}
/* If any row exist in the result set, record that fact and abort.
*/
case SRT_Exists: {
sqlite3VdbeAddOp2(v, OP_Integer, 1, iParm);
/* The LIMIT clause will terminate the loop for us */
break;
}
/* If this is a scalar select that is part of an expression, then
** store the results in the appropriate memory cell and break out
** of the scan loop.
*/
case SRT_Mem: {
assert( nColumn==1 );
if( pOrderBy ){
pushOntoSorter(pParse, pOrderBy, p, regResult);
}else{
sqlite3ExprCodeMove(pParse, regResult, iParm, 1);
/* The LIMIT clause will jump out of the loop for us */
}
break;
}
#endif /* #ifndef SQLITE_OMIT_SUBQUERY */
/* Send the data to the callback function or to a subroutine. In the
** case of a subroutine, the subroutine itself is responsible for
** popping the data from the stack.
*/
case SRT_Coroutine:
case SRT_Callback: {
if( pOrderBy ){
int r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
pushOntoSorter(pParse, pOrderBy, p, r1);
sqlite3ReleaseTempReg(pParse, r1);
}else if( eDest==SRT_Coroutine ){
sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm);
}else{
sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nColumn);
sqlite3ExprCacheAffinityChange(pParse, regResult, nColumn);
}
break;
}
#if !defined(SQLITE_OMIT_TRIGGER)
/* Discard the results. This is used for SELECT statements inside
** the body of a TRIGGER. The purpose of such selects is to call
** user-defined functions that have side effects. We do not care
** about the actual results of the select.
*/
default: {
assert( eDest==SRT_Discard );
break;
}
#endif
}
/* Jump to the end of the loop if the LIMIT is reached.
*/
if( p->iLimit ){
assert( pOrderBy==0 ); /* If there is an ORDER BY, the call to
** pushOntoSorter() would have cleared p->iLimit */
sqlite3VdbeAddOp2(v, OP_AddImm, p->iLimit, -1);
sqlite3VdbeAddOp2(v, OP_IfZero, p->iLimit, iBreak);
}
}
/*
** Given an expression list, generate a KeyInfo structure that records
** the collating sequence for each expression in that expression list.
**
** If the ExprList is an ORDER BY or GROUP BY clause then the resulting
** KeyInfo structure is appropriate for initializing a virtual index to
** implement that clause. If the ExprList is the result set of a SELECT
** then the KeyInfo structure is appropriate for initializing a virtual
** index to implement a DISTINCT test.
**
** Space to hold the KeyInfo structure is obtain from malloc. The calling
** function is responsible for seeing that this structure is eventually
** freed. Add the KeyInfo structure to the P4 field of an opcode using
** P4_KEYINFO_HANDOFF is the usual way of dealing with this.
*/
static KeyInfo *keyInfoFromExprList(Parse *pParse, ExprList *pList){
sqlite3 *db = pParse->db;
int nExpr;
KeyInfo *pInfo;
struct ExprList_item *pItem;
int i;
nExpr = pList->nExpr;
pInfo = sqlite3DbMallocZero(db, sizeof(*pInfo) + nExpr*(sizeof(CollSeq*)+1) );
if( pInfo ){
pInfo->aSortOrder = (u8*)&pInfo->aColl[nExpr];
pInfo->nField = nExpr;
pInfo->enc = ENC(db);
for(i=0, pItem=pList->a; i<nExpr; i++, pItem++){
CollSeq *pColl;
pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
if( !pColl ){
pColl = db->pDfltColl;
}
pInfo->aColl[i] = pColl;
pInfo->aSortOrder[i] = pItem->sortOrder;
}
}
return pInfo;
}
/*
** If the inner loop was generated using a non-null pOrderBy argument,
** then the results were placed in a sorter. After the loop is terminated
** we need to run the sorter and output the results. The following
** routine generates the code needed to do that.
*/
static void generateSortTail(
Parse *pParse, /* Parsing context */
Select *p, /* The SELECT statement */
Vdbe *v, /* Generate code into this VDBE */
int nColumn, /* Number of columns of data */
SelectDest *pDest /* Write the sorted results here */
){
int brk = sqlite3VdbeMakeLabel(v);
int cont = sqlite3VdbeMakeLabel(v);
int addr;
int iTab;
int pseudoTab = 0;
ExprList *pOrderBy = p->pOrderBy;
int eDest = pDest->eDest;
int iParm = pDest->iParm;
int regRow;
int regRowid;
iTab = pOrderBy->iECursor;
if( eDest==SRT_Callback || eDest==SRT_Coroutine ){
pseudoTab = pParse->nTab++;
sqlite3VdbeAddOp2(v, OP_SetNumColumns, 0, nColumn);
sqlite3VdbeAddOp2(v, OP_OpenPseudo, pseudoTab, eDest==SRT_Callback);
}
addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, brk);
codeOffset(v, p, cont);
regRow = sqlite3GetTempReg(pParse);
regRowid = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_Column, iTab, pOrderBy->nExpr + 1, regRow);
switch( eDest ){
case SRT_Table:
case SRT_EphemTab: {
sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, regRowid);
sqlite3VdbeAddOp3(v, OP_Insert, iParm, regRow, regRowid);
sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
case SRT_Set: {
assert( nColumn==1 );
sqlite3VdbeAddOp4(v, OP_MakeRecord, regRow, 1, regRowid, &p->affinity, 1);
sqlite3ExprCacheAffinityChange(pParse, regRow, 1);
sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, regRowid);
break;
}
case SRT_Mem: {
assert( nColumn==1 );
sqlite3ExprCodeMove(pParse, regRow, iParm, 1);
/* The LIMIT clause will terminate the loop for us */
break;
}
#endif
case SRT_Callback:
case SRT_Coroutine: {
int i;
sqlite3VdbeAddOp2(v, OP_Integer, 1, regRowid);
sqlite3VdbeAddOp3(v, OP_Insert, pseudoTab, regRow, regRowid);
for(i=0; i<nColumn; i++){
assert( regRow!=pDest->iMem+i );
sqlite3VdbeAddOp3(v, OP_Column, pseudoTab, i, pDest->iMem+i);
}
if( eDest==SRT_Callback ){
sqlite3VdbeAddOp2(v, OP_ResultRow, pDest->iMem, nColumn);
sqlite3ExprCacheAffinityChange(pParse, pDest->iMem, nColumn);
}else{
sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm);
}
break;
}
default: {
/* Do nothing */
break;
}
}
sqlite3ReleaseTempReg(pParse, regRow);
sqlite3ReleaseTempReg(pParse, regRowid);
/* LIMIT has been implemented by the pushOntoSorter() routine.
*/
assert( p->iLimit==0 );
/* The bottom of the loop
*/
sqlite3VdbeResolveLabel(v, cont);
sqlite3VdbeAddOp2(v, OP_Next, iTab, addr);
sqlite3VdbeResolveLabel(v, brk);
if( eDest==SRT_Callback || eDest==SRT_Coroutine ){
sqlite3VdbeAddOp2(v, OP_Close, pseudoTab, 0);
}
}
/*
** Return a pointer to a string containing the 'declaration type' of the
** expression pExpr. The string may be treated as static by the caller.
**
** The declaration type is the exact datatype definition extracted from the
** original CREATE TABLE statement if the expression is a column. The
** declaration type for a ROWID field is INTEGER. Exactly when an expression
** is considered a column can be complex in the presence of subqueries. The
** result-set expression in all of the following SELECT statements is
** considered a column by this function.
**
** SELECT col FROM tbl;
** SELECT (SELECT col FROM tbl;
** SELECT (SELECT col FROM tbl);
** SELECT abc FROM (SELECT col AS abc FROM tbl);
**
** The declaration type for any expression other than a column is NULL.
*/
static const char *columnType(
NameContext *pNC,
Expr *pExpr,
const char **pzOriginDb,
const char **pzOriginTab,
const char **pzOriginCol
){
char const *zType = 0;
char const *zOriginDb = 0;
char const *zOriginTab = 0;
char const *zOriginCol = 0;
int j;
if( pExpr==0 || pNC->pSrcList==0 ) return 0;
switch( pExpr->op ){
case TK_AGG_COLUMN:
case TK_COLUMN: {
/* The expression is a column. Locate the table the column is being
** extracted from in NameContext.pSrcList. This table may be real
** database table or a subquery.
*/
Table *pTab = 0; /* Table structure column is extracted from */
Select *pS = 0; /* Select the column is extracted from */
int iCol = pExpr->iColumn; /* Index of column in pTab */
while( pNC && !pTab ){
SrcList *pTabList = pNC->pSrcList;
for(j=0;j<pTabList->nSrc && pTabList->a[j].iCursor!=pExpr->iTable;j++);
if( j<pTabList->nSrc ){
pTab = pTabList->a[j].pTab;
pS = pTabList->a[j].pSelect;
}else{
pNC = pNC->pNext;
}
}
if( pTab==0 ){
/* FIX ME:
** This can occurs if you have something like "SELECT new.x;" inside
** a trigger. In other words, if you reference the special "new"
** table in the result set of a select. We do not have a good way
** to find the actual table type, so call it "TEXT". This is really
** something of a bug, but I do not know how to fix it.
**
** This code does not produce the correct answer - it just prevents
** a segfault. See ticket #1229.
*/
zType = "TEXT";
break;
}
assert( pTab );
if( pS ){
/* The "table" is actually a sub-select or a view in the FROM clause
** of the SELECT statement. Return the declaration type and origin
** data for the result-set column of the sub-select.
*/
if( iCol>=0 && iCol<pS->pEList->nExpr ){
/* If iCol is less than zero, then the expression requests the
** rowid of the sub-select or view. This expression is legal (see
** test case misc2.2.2) - it always evaluates to NULL.
*/
NameContext sNC;
Expr *p = pS->pEList->a[iCol].pExpr;
sNC.pSrcList = pS->pSrc;
sNC.pNext = 0;
sNC.pParse = pNC->pParse;
zType = columnType(&sNC, p, &zOriginDb, &zOriginTab, &zOriginCol);
}
}else if( pTab->pSchema ){
/* A real table */
assert( !pS );
if( iCol<0 ) iCol = pTab->iPKey;
assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
if( iCol<0 ){
zType = "INTEGER";
zOriginCol = "rowid";
}else{
zType = pTab->aCol[iCol].zType;
zOriginCol = pTab->aCol[iCol].zName;
}
zOriginTab = pTab->zName;
if( pNC->pParse ){
int iDb = sqlite3SchemaToIndex(pNC->pParse->db, pTab->pSchema);
zOriginDb = pNC->pParse->db->aDb[iDb].zName;
}
}
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
case TK_SELECT: {
/* The expression is a sub-select. Return the declaration type and
** origin info for the single column in the result set of the SELECT
** statement.
*/
NameContext sNC;
Select *pS = pExpr->pSelect;
Expr *p = pS->pEList->a[0].pExpr;
sNC.pSrcList = pS->pSrc;
sNC.pNext = pNC;
sNC.pParse = pNC->pParse;
zType = columnType(&sNC, p, &zOriginDb, &zOriginTab, &zOriginCol);
break;
}
#endif
}
if( pzOriginDb ){
assert( pzOriginTab && pzOriginCol );
*pzOriginDb = zOriginDb;
*pzOriginTab = zOriginTab;
*pzOriginCol = zOriginCol;
}
return zType;
}
/*
** Generate code that will tell the VDBE the declaration types of columns
** in the result set.
*/
static void generateColumnTypes(
Parse *pParse, /* Parser context */
SrcList *pTabList, /* List of tables */
ExprList *pEList /* Expressions defining the result set */
){
#ifndef SQLITE_OMIT_DECLTYPE
Vdbe *v = pParse->pVdbe;
int i;
NameContext sNC;
sNC.pSrcList = pTabList;
sNC.pParse = pParse;
for(i=0; i<pEList->nExpr; i++){
Expr *p = pEList->a[i].pExpr;
const char *zType;
#ifdef SQLITE_ENABLE_COLUMN_METADATA
const char *zOrigDb = 0;
const char *zOrigTab = 0;
const char *zOrigCol = 0;
zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol);
/* The vdbe must make its own copy of the column-type and other
** column specific strings, in case the schema is reset before this
** virtual machine is deleted.
*/
sqlite3VdbeSetColName(v, i, COLNAME_DATABASE, zOrigDb, P4_TRANSIENT);
sqlite3VdbeSetColName(v, i, COLNAME_TABLE, zOrigTab, P4_TRANSIENT);
sqlite3VdbeSetColName(v, i, COLNAME_COLUMN, zOrigCol, P4_TRANSIENT);
#else
zType = columnType(&sNC, p, 0, 0, 0);
#endif
sqlite3VdbeSetColName(v, i, COLNAME_DECLTYPE, zType, P4_TRANSIENT);
}
#endif /* SQLITE_OMIT_DECLTYPE */
}
/*
** Generate code that will tell the VDBE the names of columns
** in the result set. This information is used to provide the
** azCol[] values in the callback.
*/
static void generateColumnNames(
Parse *pParse, /* Parser context */
SrcList *pTabList, /* List of tables */
ExprList *pEList /* Expressions defining the result set */
){
Vdbe *v = pParse->pVdbe;
int i, j;
sqlite3 *db = pParse->db;
int fullNames, shortNames;
#ifndef SQLITE_OMIT_EXPLAIN
/* If this is an EXPLAIN, skip this step */
if( pParse->explain ){
return;
}
#endif
assert( v!=0 );
if( pParse->colNamesSet || v==0 || db->mallocFailed ) return;
pParse->colNamesSet = 1;
fullNames = (db->flags & SQLITE_FullColNames)!=0;
shortNames = (db->flags & SQLITE_ShortColNames)!=0;
sqlite3VdbeSetNumCols(v, pEList->nExpr);
for(i=0; i<pEList->nExpr; i++){
Expr *p;
p = pEList->a[i].pExpr;
if( p==0 ) continue;
if( pEList->a[i].zName ){
char *zName = pEList->a[i].zName;
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, strlen(zName));
}else if( p->op==TK_COLUMN && pTabList ){
Table *pTab;
char *zCol;
int iCol = p->iColumn;
for(j=0; j<pTabList->nSrc && pTabList->a[j].iCursor!=p->iTable; j++){}
assert( j<pTabList->nSrc );
pTab = pTabList->a[j].pTab;
if( iCol<0 ) iCol = pTab->iPKey;
assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
if( iCol<0 ){
zCol = "rowid";
}else{
zCol = pTab->aCol[iCol].zName;
}
if( !shortNames && !fullNames ){
sqlite3VdbeSetColName(v, i, COLNAME_NAME, (char*)p->span.z, p->span.n);
}else if( fullNames || (!shortNames && pTabList->nSrc>1) ){
char *zName = 0;
char *zTab;
zTab = pTabList->a[j].zAlias;
if( fullNames || zTab==0 ) zTab = pTab->zName;
zName = sqlite3MPrintf(db, "%s.%s", zTab, zCol);
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, P4_DYNAMIC);
}else{
sqlite3VdbeSetColName(v, i, COLNAME_NAME, zCol, strlen(zCol));
}
}else{
sqlite3VdbeSetColName(v, i, COLNAME_NAME, (char*)p->span.z, p->span.n);
}
}
generateColumnTypes(pParse, pTabList, pEList);
}
#ifndef SQLITE_OMIT_COMPOUND_SELECT
/*
** Name of the connection operator, used for error messages.
*/
static const char *selectOpName(int id){
char *z;
switch( id ){
case TK_ALL: z = "UNION ALL"; break;
case TK_INTERSECT: z = "INTERSECT"; break;
case TK_EXCEPT: z = "EXCEPT"; break;
default: z = "UNION"; break;
}
return z;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */
/*
** Forward declaration
*/
static int prepSelectStmt(Parse*, Select*);
/*
** Given a SELECT statement, generate a Table structure that describes
** the result set of that SELECT.
*/
Table *sqlite3ResultSetOfSelect(Parse *pParse, char *zTabName, Select *pSelect){
Table *pTab;
int i, j, rc;
ExprList *pEList;
Column *aCol, *pCol;
sqlite3 *db = pParse->db;
int savedFlags;
savedFlags = db->flags;
db->flags &= ~SQLITE_FullColNames;
db->flags |= SQLITE_ShortColNames;
rc = sqlite3SelectResolve(pParse, pSelect, 0);
if( rc==SQLITE_OK ){
while( pSelect->pPrior ) pSelect = pSelect->pPrior;
rc = prepSelectStmt(pParse, pSelect);
if( rc==SQLITE_OK ){
rc = sqlite3SelectResolve(pParse, pSelect, 0);
}
}
db->flags = savedFlags;
if( rc ){
return 0;
}
pTab = sqlite3DbMallocZero(db, sizeof(Table) );
if( pTab==0 ){
return 0;
}
pTab->db = db;
pTab->nRef = 1;
pTab->zName = zTabName ? sqlite3DbStrDup(db, zTabName) : 0;
pEList = pSelect->pEList;
pTab->nCol = pEList->nExpr;
assert( pTab->nCol>0 );
pTab->aCol = aCol = sqlite3DbMallocZero(db, sizeof(pTab->aCol[0])*pTab->nCol);
testcase( aCol==0 );
for(i=0, pCol=aCol; i<pTab->nCol; i++, pCol++){
Expr *p;
char *zType;
char *zName;
int nName;
CollSeq *pColl;
int cnt;
NameContext sNC;
/* Get an appropriate name for the column
*/
p = pEList->a[i].pExpr;
assert( p->pRight==0 || p->pRight->token.z==0 || p->pRight->token.z[0]!=0 );
if( (zName = pEList->a[i].zName)!=0 ){
/* If the column contains an "AS <name>" phrase, use <name> as the name */
zName = sqlite3DbStrDup(db, zName);
}else if( p->op==TK_COLUMN && p->pTab ){
/* For columns use the column name name */
int iCol = p->iColumn;
if( iCol<0 ) iCol = p->pTab->iPKey;
zName = sqlite3MPrintf(db, "%s", p->pTab->aCol[iCol].zName);
}else{
/* Use the original text of the column expression as its name */
zName = sqlite3MPrintf(db, "%T", &p->span);
}
if( db->mallocFailed ){
sqlite3DbFree(db, zName);
break;
}
sqlite3Dequote(zName);
/* Make sure the column name is unique. If the name is not unique,
** append a integer to the name so that it becomes unique.
*/
nName = strlen(zName);
for(j=cnt=0; j<i; j++){
if( sqlite3StrICmp(aCol[j].zName, zName)==0 ){
char *zNewName;
zName[nName] = 0;
zNewName = sqlite3MPrintf(db, "%s:%d", zName, ++cnt);
sqlite3DbFree(db, zName);
zName = zNewName;
j = -1;
if( zName==0 ) break;
}
}
pCol->zName = zName;
/* Get the typename, type affinity, and collating sequence for the
** column.
*/
memset(&sNC, 0, sizeof(sNC));
sNC.pSrcList = pSelect->pSrc;
zType = sqlite3DbStrDup(db, columnType(&sNC, p, 0, 0, 0));
pCol->zType = zType;
pCol->affinity = sqlite3ExprAffinity(p);
pColl = sqlite3ExprCollSeq(pParse, p);
if( pColl ){
pCol->zColl = sqlite3DbStrDup(db, pColl->zName);
}
}
pTab->iPKey = -1;
if( db->mallocFailed ){
sqlite3DeleteTable(pTab);
return 0;
}
return pTab;
}
/*
** Prepare a SELECT statement for processing by doing the following
** things:
**
** (1) Make sure VDBE cursor numbers have been assigned to every
** element of the FROM clause.
**
** (2) Fill in the pTabList->a[].pTab fields in the SrcList that
** defines FROM clause. When views appear in the FROM clause,
** fill pTabList->a[].pSelect with a copy of the SELECT statement
** that implements the view. A copy is made of the view's SELECT
** statement so that we can freely modify or delete that statement
** without worrying about messing up the presistent representation
** of the view.
**
** (3) Add terms to the WHERE clause to accomodate the NATURAL keyword
** on joins and the ON and USING clause of joins.
**
** (4) Scan the list of columns in the result set (pEList) looking
** for instances of the "*" operator or the TABLE.* operator.
** If found, expand each "*" to be every column in every table
** and TABLE.* to be every column in TABLE.
**
** Return 0 on success. If there are problems, leave an error message
** in pParse and return non-zero.
*/
static int prepSelectStmt(Parse *pParse, Select *p){
int i, j, k, rc;
SrcList *pTabList;
ExprList *pEList;
struct SrcList_item *pFrom;
sqlite3 *db = pParse->db;
if( p==0 || p->pSrc==0 || db->mallocFailed ){
return 1;
}
pTabList = p->pSrc;
pEList = p->pEList;
/* Make sure cursor numbers have been assigned to all entries in
** the FROM clause of the SELECT statement.
*/
sqlite3SrcListAssignCursors(pParse, p->pSrc);
/* Look up every table named in the FROM clause of the select. If
** an entry of the FROM clause is a subquery instead of a table or view,
** then create a transient table structure to describe the subquery.
*/
for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
Table *pTab;
if( pFrom->pTab!=0 ){
/* This statement has already been prepared. There is no need
** to go further. */
assert( i==0 );
return 0;
}
if( pFrom->zName==0 ){
#ifndef SQLITE_OMIT_SUBQUERY
/* A sub-query in the FROM clause of a SELECT */
assert( pFrom->pSelect!=0 );
if( pFrom->zAlias==0 ){
pFrom->zAlias =
sqlite3MPrintf(db, "sqlite_subquery_%p_", (void*)pFrom->pSelect);
}
assert( pFrom->pTab==0 );
pFrom->pTab = pTab =
sqlite3ResultSetOfSelect(pParse, pFrom->zAlias, pFrom->pSelect);
if( pTab==0 ){
return 1;
}
/* The isEphem flag indicates that the Table structure has been
** dynamically allocated and may be freed at any time. In other words,
** pTab is not pointing to a persistent table structure that defines
** part of the schema. */
pTab->isEphem = 1;
#endif
}else{
/* An ordinary table or view name in the FROM clause */
assert( pFrom->pTab==0 );
pFrom->pTab = pTab =
sqlite3LocateTable(pParse,0,pFrom->zName,pFrom->zDatabase);
if( pTab==0 ){
return 1;
}
pTab->nRef++;
#if !defined(SQLITE_OMIT_VIEW) || !defined (SQLITE_OMIT_VIRTUALTABLE)
if( pTab->pSelect || IsVirtual(pTab) ){
/* We reach here if the named table is a really a view */
if( sqlite3ViewGetColumnNames(pParse, pTab) ){
return 1;
}
/* If pFrom->pSelect!=0 it means we are dealing with a
** view within a view. The SELECT structure has already been
** copied by the outer view so we can skip the copy step here
** in the inner view.
*/
if( pFrom->pSelect==0 ){
pFrom->pSelect = sqlite3SelectDup(db, pTab->pSelect);
}
}
#endif
}
}
/* Process NATURAL keywords, and ON and USING clauses of joins.
*/
if( sqliteProcessJoin(pParse, p) ) return 1;
/* For every "*" that occurs in the column list, insert the names of
** all columns in all tables. And for every TABLE.* insert the names
** of all columns in TABLE. The parser inserted a special expression
** with the TK_ALL operator for each "*" that it found in the column list.
** The following code just has to locate the TK_ALL expressions and expand
** each one to the list of all columns in all tables.
**
** The first loop just checks to see if there are any "*" operators
** that need expanding.
*/
for(k=0; k<pEList->nExpr; k++){
Expr *pE = pEList->a[k].pExpr;
if( pE->op==TK_ALL ) break;
if( pE->op==TK_DOT && pE->pRight && pE->pRight->op==TK_ALL
&& pE->pLeft && pE->pLeft->op==TK_ID ) break;
}
rc = 0;
if( k<pEList->nExpr ){
/*
** If we get here it means the result set contains one or more "*"
** operators that need to be expanded. Loop through each expression
** in the result set and expand them one by one.
*/
struct ExprList_item *a = pEList->a;
ExprList *pNew = 0;
int flags = pParse->db->flags;
int longNames = (flags & SQLITE_FullColNames)!=0
&& (flags & SQLITE_ShortColNames)==0;
for(k=0; k<pEList->nExpr; k++){
Expr *pE = a[k].pExpr;
if( pE->op!=TK_ALL &&
(pE->op!=TK_DOT || pE->pRight==0 || pE->pRight->op!=TK_ALL) ){
/* This particular expression does not need to be expanded.
*/
pNew = sqlite3ExprListAppend(pParse, pNew, a[k].pExpr, 0);
if( pNew ){
pNew->a[pNew->nExpr-1].zName = a[k].zName;
}else{
rc = 1;
}
a[k].pExpr = 0;
a[k].zName = 0;
}else{
/* This expression is a "*" or a "TABLE.*" and needs to be
** expanded. */
int tableSeen = 0; /* Set to 1 when TABLE matches */
char *zTName; /* text of name of TABLE */
if( pE->op==TK_DOT && pE->pLeft ){
zTName = sqlite3NameFromToken(db, &pE->pLeft->token);
}else{
zTName = 0;
}
for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
Table *pTab = pFrom->pTab;
char *zTabName = pFrom->zAlias;
if( zTabName==0 || zTabName[0]==0 ){
zTabName = pTab->zName;
}
assert( zTabName );
if( zTName && sqlite3StrICmp(zTName, zTabName)!=0 ){
continue;
}
tableSeen = 1;
for(j=0; j<pTab->nCol; j++){
Expr *pExpr, *pRight;
char *zName = pTab->aCol[j].zName;
/* If a column is marked as 'hidden' (currently only possible
** for virtual tables), do not include it in the expanded
** result-set list.
*/
if( IsHiddenColumn(&pTab->aCol[j]) ){
assert(IsVirtual(pTab));
continue;
}
if( i>0 ){
struct SrcList_item *pLeft = &pTabList->a[i-1];
if( (pLeft[1].jointype & JT_NATURAL)!=0 &&
columnIndex(pLeft->pTab, zName)>=0 ){
/* In a NATURAL join, omit the join columns from the
** table on the right */
continue;
}
if( sqlite3IdListIndex(pLeft[1].pUsing, zName)>=0 ){
/* In a join with a USING clause, omit columns in the
** using clause from the table on the right. */
continue;
}
}
pRight = sqlite3PExpr(pParse, TK_ID, 0, 0, 0);
if( pRight==0 ) break;
setQuotedToken(pParse, &pRight->token, zName);
if( longNames || pTabList->nSrc>1 ){
Expr *pLeft = sqlite3PExpr(pParse, TK_ID, 0, 0, 0);
pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pRight, 0);
if( pExpr==0 ) break;
setQuotedToken(pParse, &pLeft->token, zTabName);
#if 1
setToken(&pExpr->span,
sqlite3MPrintf(db, "%s.%s", zTabName, zName));
pExpr->span.dyn = 1;
#else
pExpr->span = pRight->token;
pExpr->span.dyn = 0;
#endif
pExpr->token.z = 0;
pExpr->token.n = 0;
pExpr->token.dyn = 0;
}else{
pExpr = pRight;
pExpr->span = pExpr->token;
pExpr->span.dyn = 0;
}
if( longNames ){
pNew = sqlite3ExprListAppend(pParse, pNew, pExpr, &pExpr->span);
}else{
pNew = sqlite3ExprListAppend(pParse, pNew, pExpr, &pRight->token);
}
}
}
if( !tableSeen ){
if( zTName ){
sqlite3ErrorMsg(pParse, "no such table: %s", zTName);
}else{
sqlite3ErrorMsg(pParse, "no tables specified");
}
rc = 1;
}
sqlite3DbFree(db, zTName);
}
}
sqlite3ExprListDelete(db, pEList);
p->pEList = pNew;
}
#if SQLITE_MAX_COLUMN
if( p->pEList && p->pEList->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){
sqlite3ErrorMsg(pParse, "too many columns in result set");
rc = SQLITE_ERROR;
}
#endif
if( db->mallocFailed ){
rc = SQLITE_NOMEM;
}
return rc;
}
/*
** pE is a pointer to an expression which is a single term in
** ORDER BY or GROUP BY clause.
**
** At the point this routine is called, we already know that the
** ORDER BY term is not an integer index into the result set. That
** casee is handled by the calling routine.
**
** If pE is a well-formed expression and the SELECT statement
** is not compound, then return 0. This indicates to the
** caller that it should sort by the value of the ORDER BY
** expression.
**
** If the SELECT is compound, then attempt to match pE against
** result set columns in the left-most SELECT statement. Return
** the index i of the matching column, as an indication to the
** caller that it should sort by the i-th column. If there is
** no match, return -1 and leave an error message in pParse.
*/
static int matchOrderByTermToExprList(
Parse *pParse, /* Parsing context for error messages */
Select *pSelect, /* The SELECT statement with the ORDER BY clause */
Expr *pE, /* The specific ORDER BY term */
int idx, /* When ORDER BY term is this */
int isCompound, /* True if this is a compound SELECT */
u8 *pHasAgg /* True if expression contains aggregate functions */
){
int i; /* Loop counter */
ExprList *pEList; /* The columns of the result set */
NameContext nc; /* Name context for resolving pE */
assert( sqlite3ExprIsInteger(pE, &i)==0 );
pEList = pSelect->pEList;
/* If the term is a simple identifier that try to match that identifier
** against a column name in the result set.
*/
if( pE->op==TK_ID || (pE->op==TK_STRING && pE->token.z[0]!='\'') ){
sqlite3 *db = pParse->db;
char *zCol = sqlite3NameFromToken(db, &pE->token);
if( zCol==0 ){
return -1;
}
for(i=0; i<pEList->nExpr; i++){
char *zAs = pEList->a[i].zName;
if( zAs!=0 && sqlite3StrICmp(zAs, zCol)==0 ){
sqlite3DbFree(db, zCol);
return i+1;
}
}
sqlite3DbFree(db, zCol);
}
/* Resolve all names in the ORDER BY term expression
*/
memset(&nc, 0, sizeof(nc));
nc.pParse = pParse;
nc.pSrcList = pSelect->pSrc;
nc.pEList = pEList;
nc.allowAgg = 1;
nc.nErr = 0;
if( sqlite3ExprResolveNames(&nc, pE) ){
if( isCompound ){
sqlite3ErrorClear(pParse);
return 0;
}else{
return -1;
}
}
if( nc.hasAgg && pHasAgg ){
*pHasAgg = 1;
}
/* For a compound SELECT, we need to try to match the ORDER BY
** expression against an expression in the result set
*/
if( isCompound ){
for(i=0; i<pEList->nExpr; i++){
if( sqlite3ExprCompare(pEList->a[i].pExpr, pE) ){
return i+1;
}
}
}
return 0;
}
/*
** Analyze and ORDER BY or GROUP BY clause in a simple SELECT statement.
** Return the number of errors seen.
**
** Every term of the ORDER BY or GROUP BY clause needs to be an
** expression. If any expression is an integer constant, then
** that expression is replaced by the corresponding
** expression from the result set.
*/
static int processOrderGroupBy(
Parse *pParse, /* Parsing context. Leave error messages here */
Select *pSelect, /* The SELECT statement containing the clause */
ExprList *pOrderBy, /* The ORDER BY or GROUP BY clause to be processed */
int isOrder, /* 1 for ORDER BY. 0 for GROUP BY */
u8 *pHasAgg /* Set to TRUE if any term contains an aggregate */
){
int i;
sqlite3 *db = pParse->db;
ExprList *pEList;
if( pOrderBy==0 || pParse->db->mallocFailed ) return 0;
#if SQLITE_MAX_COLUMN
if( pOrderBy->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){
const char *zType = isOrder ? "ORDER" : "GROUP";
sqlite3ErrorMsg(pParse, "too many terms in %s BY clause", zType);
return 1;
}
#endif
pEList = pSelect->pEList;
if( pEList==0 ){
return 0;
}
for(i=0; i<pOrderBy->nExpr; i++){
int iCol;
Expr *pE = pOrderBy->a[i].pExpr;
if( sqlite3ExprIsInteger(pE, &iCol) ){
if( iCol<=0 || iCol>pEList->nExpr ){
const char *zType = isOrder ? "ORDER" : "GROUP";
sqlite3ErrorMsg(pParse,
"%r %s BY term out of range - should be "
"between 1 and %d", i+1, zType, pEList->nExpr);
return 1;
}
}else{
iCol = matchOrderByTermToExprList(pParse, pSelect, pE, i+1, 0, pHasAgg);
if( iCol<0 ){
return 1;
}
}
if( iCol>0 ){
CollSeq *pColl = pE->pColl;
int flags = pE->flags & EP_ExpCollate;
sqlite3ExprDelete(db, pE);
pE = sqlite3ExprDup(db, pEList->a[iCol-1].pExpr);
pOrderBy->a[i].pExpr = pE;
if( pE && pColl && flags ){
pE->pColl = pColl;
pE->flags |= flags;
}
}
}
return 0;
}
/*
** Analyze and ORDER BY or GROUP BY clause in a SELECT statement. Return
** the number of errors seen.
**
** If iTable>0 then make the N-th term of the ORDER BY clause refer to
** the N-th column of table iTable.
**
** If iTable==0 then transform each term of the ORDER BY clause to refer
** to a column of the result set by number.
*/
static int processCompoundOrderBy(
Parse *pParse, /* Parsing context. Leave error messages here */
Select *pSelect /* The SELECT statement containing the ORDER BY */
){
int i;
ExprList *pOrderBy;
ExprList *pEList;
sqlite3 *db;
int moreToDo = 1;
pOrderBy = pSelect->pOrderBy;
if( pOrderBy==0 ) return 0;
db = pParse->db;
#if SQLITE_MAX_COLUMN
if( pOrderBy->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){
sqlite3ErrorMsg(pParse, "too many terms in ORDER BY clause");
return 1;
}
#endif
for(i=0; i<pOrderBy->nExpr; i++){
pOrderBy->a[i].done = 0;
}
while( pSelect->pPrior ){
pSelect = pSelect->pPrior;
}
while( pSelect && moreToDo ){
moreToDo = 0;
pEList = pSelect->pEList;
if( pEList==0 ){
return 1;
}
for(i=0; i<pOrderBy->nExpr; i++){
int iCol = -1;
Expr *pE, *pDup;
if( pOrderBy->a[i].done ) continue;
pE = pOrderBy->a[i].pExpr;
if( sqlite3ExprIsInteger(pE, &iCol) ){
if( iCol<0 || iCol>pEList->nExpr ){
sqlite3ErrorMsg(pParse,
"%r ORDER BY term out of range - should be "
"between 1 and %d", i+1, pEList->nExpr);
return 1;
}
}else{
pDup = sqlite3ExprDup(db, pE);
if( !db->mallocFailed ){
assert(pDup);
iCol = matchOrderByTermToExprList(pParse, pSelect, pDup, i+1, 1, 0);
}
sqlite3ExprDelete(db, pDup);
if( iCol<0 ){
return 1;
}
}
if( iCol>0 ){
pE->op = TK_INTEGER;
pE->flags |= EP_IntValue;
pE->iTable = iCol;
pOrderBy->a[i].done = 1;
}else{
moreToDo = 1;
}
}
pSelect = pSelect->pNext;
}
for(i=0; i<pOrderBy->nExpr; i++){
if( pOrderBy->a[i].done==0 ){
sqlite3ErrorMsg(pParse, "%r ORDER BY term does not match any "
"column in the result set", i+1);
return 1;
}
}
return 0;
}
/*
** Get a VDBE for the given parser context. Create a new one if necessary.
** If an error occurs, return NULL and leave a message in pParse.
*/
Vdbe *sqlite3GetVdbe(Parse *pParse){
Vdbe *v = pParse->pVdbe;
if( v==0 ){
v = pParse->pVdbe = sqlite3VdbeCreate(pParse->db);
#ifndef SQLITE_OMIT_TRACE
if( v ){
sqlite3VdbeAddOp0(v, OP_Trace);
}
#endif
}
return v;
}
/*
** Compute the iLimit and iOffset fields of the SELECT based on the
** pLimit and pOffset expressions. pLimit and pOffset hold the expressions
** that appear in the original SQL statement after the LIMIT and OFFSET
** keywords. Or NULL if those keywords are omitted. iLimit and iOffset
** are the integer memory register numbers for counters used to compute
** the limit and offset. If there is no limit and/or offset, then
** iLimit and iOffset are negative.
**
** This routine changes the values of iLimit and iOffset only if
** a limit or offset is defined by pLimit and pOffset. iLimit and
** iOffset should have been preset to appropriate default values
** (usually but not always -1) prior to calling this routine.
** Only if pLimit!=0 or pOffset!=0 do the limit registers get
** redefined. The UNION ALL operator uses this property to force
** the reuse of the same limit and offset registers across multiple
** SELECT statements.
*/
static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){
Vdbe *v = 0;
int iLimit = 0;
int iOffset;
int addr1;
if( p->iLimit ) return;
/*
** "LIMIT -1" always shows all rows. There is some
** contraversy about what the correct behavior should be.
** The current implementation interprets "LIMIT 0" to mean
** no rows.
*/
if( p->pLimit ){
p->iLimit = iLimit = ++pParse->nMem;
v = sqlite3GetVdbe(pParse);
if( v==0 ) return;
sqlite3ExprCode(pParse, p->pLimit, iLimit);
sqlite3VdbeAddOp1(v, OP_MustBeInt, iLimit);
VdbeComment((v, "LIMIT counter"));
sqlite3VdbeAddOp2(v, OP_IfZero, iLimit, iBreak);
}
if( p->pOffset ){
p->iOffset = iOffset = ++pParse->nMem;
if( p->pLimit ){
pParse->nMem++; /* Allocate an extra register for limit+offset */
}
v = sqlite3GetVdbe(pParse);
if( v==0 ) return;
sqlite3ExprCode(pParse, p->pOffset, iOffset);
sqlite3VdbeAddOp1(v, OP_MustBeInt, iOffset);
VdbeComment((v, "OFFSET counter"));
addr1 = sqlite3VdbeAddOp1(v, OP_IfPos, iOffset);
sqlite3VdbeAddOp2(v, OP_Integer, 0, iOffset);
sqlite3VdbeJumpHere(v, addr1);
if( p->pLimit ){
sqlite3VdbeAddOp3(v, OP_Add, iLimit, iOffset, iOffset+1);
VdbeComment((v, "LIMIT+OFFSET"));
addr1 = sqlite3VdbeAddOp1(v, OP_IfPos, iLimit);
sqlite3VdbeAddOp2(v, OP_Integer, -1, iOffset+1);
sqlite3VdbeJumpHere(v, addr1);
}
}
}
#ifndef SQLITE_OMIT_COMPOUND_SELECT
/*
** Return the appropriate collating sequence for the iCol-th column of
** the result set for the compound-select statement "p". Return NULL if
** the column has no default collating sequence.
**
** The collating sequence for the compound select is taken from the
** left-most term of the select that has a collating sequence.
*/
static CollSeq *multiSelectCollSeq(Parse *pParse, Select *p, int iCol){
CollSeq *pRet;
if( p->pPrior ){
pRet = multiSelectCollSeq(pParse, p->pPrior, iCol);
}else{
pRet = 0;
}
if( pRet==0 ){
pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr);
}
return pRet;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */
/* Forward reference */
static int multiSelectOrderBy(
Parse *pParse, /* Parsing context */
Select *p, /* The right-most of SELECTs to be coded */
SelectDest *pDest /* What to do with query results */
);
#ifndef SQLITE_OMIT_COMPOUND_SELECT
/*
** This routine is called to process a compound query form from
** two or more separate queries using UNION, UNION ALL, EXCEPT, or
** INTERSECT
**
** "p" points to the right-most of the two queries. the query on the
** left is p->pPrior. The left query could also be a compound query
** in which case this routine will be called recursively.
**
** The results of the total query are to be written into a destination
** of type eDest with parameter iParm.
**
** Example 1: Consider a three-way compound SQL statement.
**
** SELECT a FROM t1 UNION SELECT b FROM t2 UNION SELECT c FROM t3
**
** This statement is parsed up as follows:
**
** SELECT c FROM t3
** |
** `-----> SELECT b FROM t2
** |
** `------> SELECT a FROM t1
**
** The arrows in the diagram above represent the Select.pPrior pointer.
** So if this routine is called with p equal to the t3 query, then
** pPrior will be the t2 query. p->op will be TK_UNION in this case.
**
** Notice that because of the way SQLite parses compound SELECTs, the
** individual selects always group from left to right.
*/
static int multiSelect(
Parse *pParse, /* Parsing context */
Select *p, /* The right-most of SELECTs to be coded */
SelectDest *pDest /* What to do with query results */
){
int rc = SQLITE_OK; /* Success code from a subroutine */
Select *pPrior; /* Another SELECT immediately to our left */
Vdbe *v; /* Generate code to this VDBE */
SelectDest dest; /* Alternative data destination */
Select *pDelete = 0; /* Chain of simple selects to delete */
sqlite3 *db; /* Database connection */
/* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs. Only
** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT.
*/
assert( p && p->pPrior ); /* Calling function guarantees this much */
db = pParse->db;
pPrior = p->pPrior;
assert( pPrior->pRightmost!=pPrior );
assert( pPrior->pRightmost==p->pRightmost );
if( pPrior->pOrderBy ){
sqlite3ErrorMsg(pParse,"ORDER BY clause should come after %s not before",
selectOpName(p->op));
rc = 1;
goto multi_select_end;
}
if( pPrior->pLimit ){
sqlite3ErrorMsg(pParse,"LIMIT clause should come after %s not before",
selectOpName(p->op));
rc = 1;
goto multi_select_end;
}
v = sqlite3GetVdbe(pParse);
assert( v!=0 ); /* The VDBE already created by calling function */
/* Create the destination temporary table if necessary
*/
dest = *pDest;
if( dest.eDest==SRT_EphemTab ){
assert( p->pEList );
sqlite3VdbeAddOp2(v, OP_OpenEphemeral, dest.iParm, p->pEList->nExpr);
dest.eDest = SRT_Table;
}
/* Make sure all SELECTs in the statement have the same number of elements
** in their result sets.
*/
assert( p->pEList && pPrior->pEList );
if( p->pEList->nExpr!=pPrior->pEList->nExpr ){
sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s"
" do not have the same number of result columns", selectOpName(p->op));
rc = 1;
goto multi_select_end;
}
/* Compound SELECTs that have an ORDER BY clause are handled separately.
*/
if( p->pOrderBy ){
return multiSelectOrderBy(pParse, p, pDest);
}
/* Generate code for the left and right SELECT statements.
*/
switch( p->op ){
case TK_ALL: {
int addr = 0;
assert( !pPrior->pLimit );
pPrior->pLimit = p->pLimit;
pPrior->pOffset = p->pOffset;
rc = sqlite3Select(pParse, pPrior, &dest, 0, 0, 0);
p->pLimit = 0;
p->pOffset = 0;
if( rc ){
goto multi_select_end;
}
p->pPrior = 0;
p->iLimit = pPrior->iLimit;
p->iOffset = pPrior->iOffset;
if( p->iLimit ){
addr = sqlite3VdbeAddOp1(v, OP_IfZero, p->iLimit);
VdbeComment((v, "Jump ahead if LIMIT reached"));
}
rc = sqlite3Select(pParse, p, &dest, 0, 0, 0);
pDelete = p->pPrior;
p->pPrior = pPrior;
if( rc ){
goto multi_select_end;
}
if( addr ){
sqlite3VdbeJumpHere(v, addr);
}
break;
}
case TK_EXCEPT:
case TK_UNION: {
int unionTab; /* Cursor number of the temporary table holding result */
int op = 0; /* One of the SRT_ operations to apply to self */
int priorOp; /* The SRT_ operation to apply to prior selects */
Expr *pLimit, *pOffset; /* Saved values of p->nLimit and p->nOffset */
int addr;
SelectDest uniondest;
priorOp = SRT_Union;
if( dest.eDest==priorOp && !p->pLimit && !p->pOffset ){
/* We can reuse a temporary table generated by a SELECT to our
** right.
*/
unionTab = dest.iParm;
}else{
/* We will need to create our own temporary table to hold the
** intermediate results.
*/
unionTab = pParse->nTab++;
assert( p->pOrderBy==0 );
addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, unionTab, 0);
assert( p->addrOpenEphm[0] == -1 );
p->addrOpenEphm[0] = addr;
p->pRightmost->usesEphm = 1;
assert( p->pEList );
}
/* Code the SELECT statements to our left
*/
assert( !pPrior->pOrderBy );
sqlite3SelectDestInit(&uniondest, priorOp, unionTab);
rc = sqlite3Select(pParse, pPrior, &uniondest, 0, 0, 0);
if( rc ){
goto multi_select_end;
}
/* Code the current SELECT statement
*/
if( p->op==TK_EXCEPT ){
op = SRT_Except;
}else{
assert( p->op==TK_UNION );
op = SRT_Union;
}
p->pPrior = 0;
p->disallowOrderBy = 0;
pLimit = p->pLimit;
p->pLimit = 0;
pOffset = p->pOffset;
p->pOffset = 0;
uniondest.eDest = op;
rc = sqlite3Select(pParse, p, &uniondest, 0, 0, 0);
/* Query flattening in sqlite3Select() might refill p->pOrderBy.
** Be sure to delete p->pOrderBy, therefore, to avoid a memory leak. */
sqlite3ExprListDelete(db, p->pOrderBy);
pDelete = p->pPrior;
p->pPrior = pPrior;
p->pOrderBy = 0;
sqlite3ExprDelete(db, p->pLimit);
p->pLimit = pLimit;
p->pOffset = pOffset;
p->iLimit = 0;
p->iOffset = 0;
if( rc ){
goto multi_select_end;
}
/* Convert the data in the temporary table into whatever form
** it is that we currently need.
*/
if( dest.eDest!=priorOp || unionTab!=dest.iParm ){
int iCont, iBreak, iStart;
assert( p->pEList );
if( dest.eDest==SRT_Callback ){
Select *pFirst = p;
while( pFirst->pPrior ) pFirst = pFirst->pPrior;
generateColumnNames(pParse, 0, pFirst->pEList);
}
iBreak = sqlite3VdbeMakeLabel(v);
iCont = sqlite3VdbeMakeLabel(v);
computeLimitRegisters(pParse, p, iBreak);
sqlite3VdbeAddOp2(v, OP_Rewind, unionTab, iBreak);
iStart = sqlite3VdbeCurrentAddr(v);
selectInnerLoop(pParse, p, p->pEList, unionTab, p->pEList->nExpr,
0, -1, &dest, iCont, iBreak);
sqlite3VdbeResolveLabel(v, iCont);
sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart);
sqlite3VdbeResolveLabel(v, iBreak);
sqlite3VdbeAddOp2(v, OP_Close, unionTab, 0);
}
break;
}
case TK_INTERSECT: {
int tab1, tab2;
int iCont, iBreak, iStart;
Expr *pLimit, *pOffset;
int addr;
SelectDest intersectdest;
int r1;
/* INTERSECT is different from the others since it requires
** two temporary tables. Hence it has its own case. Begin
** by allocating the tables we will need.
*/
tab1 = pParse->nTab++;
tab2 = pParse->nTab++;
assert( p->pOrderBy==0 );
addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab1, 0);
assert( p->addrOpenEphm[0] == -1 );
p->addrOpenEphm[0] = addr;
p->pRightmost->usesEphm = 1;
assert( p->pEList );
/* Code the SELECTs to our left into temporary table "tab1".
*/
sqlite3SelectDestInit(&intersectdest, SRT_Union, tab1);
rc = sqlite3Select(pParse, pPrior, &intersectdest, 0, 0, 0);
if( rc ){
goto multi_select_end;
}
/* Code the current SELECT into temporary table "tab2"
*/
addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab2, 0);
assert( p->addrOpenEphm[1] == -1 );
p->addrOpenEphm[1] = addr;
p->pPrior = 0;
pLimit = p->pLimit;
p->pLimit = 0;
pOffset = p->pOffset;
p->pOffset = 0;
intersectdest.iParm = tab2;
rc = sqlite3Select(pParse, p, &intersectdest, 0, 0, 0);
pDelete = p->pPrior;
p->pPrior = pPrior;
sqlite3ExprDelete(db, p->pLimit);
p->pLimit = pLimit;
p->pOffset = pOffset;
if( rc ){
goto multi_select_end;
}
/* Generate code to take the intersection of the two temporary
** tables.
*/
assert( p->pEList );
if( dest.eDest==SRT_Callback ){
Select *pFirst = p;
while( pFirst->pPrior ) pFirst = pFirst->pPrior;
generateColumnNames(pParse, 0, pFirst->pEList);
}
iBreak = sqlite3VdbeMakeLabel(v);
iCont = sqlite3VdbeMakeLabel(v);
computeLimitRegisters(pParse, p, iBreak);
sqlite3VdbeAddOp2(v, OP_Rewind, tab1, iBreak);
r1 = sqlite3GetTempReg(pParse);
iStart = sqlite3VdbeAddOp2(v, OP_RowKey, tab1, r1);
sqlite3VdbeAddOp3(v, OP_NotFound, tab2, iCont, r1);
sqlite3ReleaseTempReg(pParse, r1);
selectInnerLoop(pParse, p, p->pEList, tab1, p->pEList->nExpr,
0, -1, &dest, iCont, iBreak);
sqlite3VdbeResolveLabel(v, iCont);
sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart);
sqlite3VdbeResolveLabel(v, iBreak);
sqlite3VdbeAddOp2(v, OP_Close, tab2, 0);
sqlite3VdbeAddOp2(v, OP_Close, tab1, 0);
break;
}
}
/* Compute collating sequences used by
** temporary tables needed to implement the compound select.
** Attach the KeyInfo structure to all temporary tables.
**
** This section is run by the right-most SELECT statement only.
** SELECT statements to the left always skip this part. The right-most
** SELECT might also skip this part if it has no ORDER BY clause and
** no temp tables are required.
*/
if( p->usesEphm ){
int i; /* Loop counter */
KeyInfo *pKeyInfo; /* Collating sequence for the result set */
Select *pLoop; /* For looping through SELECT statements */
CollSeq **apColl; /* For looping through pKeyInfo->aColl[] */
int nCol; /* Number of columns in result set */
assert( p->pRightmost==p );
nCol = p->pEList->nExpr;
pKeyInfo = sqlite3DbMallocZero(db,
sizeof(*pKeyInfo)+nCol*(sizeof(CollSeq*) + 1));
if( !pKeyInfo ){
rc = SQLITE_NOMEM;
goto multi_select_end;
}
pKeyInfo->enc = ENC(db);
pKeyInfo->nField = nCol;
for(i=0, apColl=pKeyInfo->aColl; i<nCol; i++, apColl++){
*apColl = multiSelectCollSeq(pParse, p, i);
if( 0==*apColl ){
*apColl = db->pDfltColl;
}
}
for(pLoop=p; pLoop; pLoop=pLoop->pPrior){
for(i=0; i<2; i++){
int addr = pLoop->addrOpenEphm[i];
if( addr<0 ){
/* If [0] is unused then [1] is also unused. So we can
** always safely abort as soon as the first unused slot is found */
assert( pLoop->addrOpenEphm[1]<0 );
break;
}
sqlite3VdbeChangeP2(v, addr, nCol);
sqlite3VdbeChangeP4(v, addr, (char*)pKeyInfo, P4_KEYINFO);
pLoop->addrOpenEphm[i] = -1;
}
}
sqlite3DbFree(db, pKeyInfo);
}
multi_select_end:
pDest->iMem = dest.iMem;
pDest->nMem = dest.nMem;
sqlite3SelectDelete(db, pDelete);
return rc;
}
#endif /* SQLITE_OMIT_COMPOUND_SELECT */
/*
** Code an output subroutine for a coroutine implementation of a
** SELECT statment.
**
** The data to be output is contained in pIn->iMem. There are
** pIn->nMem columns to be output. pDest is where the output should
** be sent.
**
** regReturn is the number of the register holding the subroutine
** return address.
**
** If regPrev>0 then it is a the first register in a vector that
** records the previous output. mem[regPrev] is a flag that is false
** if there has been no previous output. If regPrev>0 then code is
** generated to suppress duplicates. pKeyInfo is used for comparing
** keys.
**
** If the LIMIT found in p->iLimit is reached, jump immediately to
** iBreak.
*/
static int generateOutputSubroutine(
Parse *pParse, /* Parsing context */
Select *p, /* The SELECT statement */
SelectDest *pIn, /* Coroutine supplying data */
SelectDest *pDest, /* Where to send the data */
int regReturn, /* The return address register */
int regPrev, /* Previous result register. No uniqueness if 0 */
KeyInfo *pKeyInfo, /* For comparing with previous entry */
int p4type, /* The p4 type for pKeyInfo */
int iBreak /* Jump here if we hit the LIMIT */
){
Vdbe *v = pParse->pVdbe;
int iContinue;
int addr;
addr = sqlite3VdbeCurrentAddr(v);
iContinue = sqlite3VdbeMakeLabel(v);
/* Suppress duplicates for UNION, EXCEPT, and INTERSECT
*/
if( regPrev ){
int j1, j2;
j1 = sqlite3VdbeAddOp1(v, OP_IfNot, regPrev);
j2 = sqlite3VdbeAddOp4(v, OP_Compare, pIn->iMem, regPrev+1, pIn->nMem,
(char*)pKeyInfo, p4type);
sqlite3VdbeAddOp3(v, OP_Jump, j2+2, iContinue, j2+2);
sqlite3VdbeJumpHere(v, j1);
sqlite3ExprCodeCopy(pParse, pIn->iMem, regPrev+1, pIn->nMem);
sqlite3VdbeAddOp2(v, OP_Integer, 1, regPrev);
}
if( pParse->db->mallocFailed ) return 0;
/* Suppress the the first OFFSET entries if there is an OFFSET clause
*/
codeOffset(v, p, iContinue);
switch( pDest->eDest ){
/* Store the result as data using a unique key.
*/
case SRT_Table:
case SRT_EphemTab: {
int r1 = sqlite3GetTempReg(pParse);
int r2 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, pIn->iMem, pIn->nMem, r1);
sqlite3VdbeAddOp2(v, OP_NewRowid, pDest->iParm, r2);
sqlite3VdbeAddOp3(v, OP_Insert, pDest->iParm, r1, r2);
sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
sqlite3ReleaseTempReg(pParse, r2);
sqlite3ReleaseTempReg(pParse, r1);
break;
}
#ifndef SQLITE_OMIT_SUBQUERY
/* If we are creating a set for an "expr IN (SELECT ...)" construct,
** then there should be a single item on the stack. Write this
** item into the set table with bogus data.
*/
case SRT_Set: {
int r1;
assert( pIn->nMem==1 );
p->affinity =
sqlite3CompareAffinity(p->pEList->a[0].pExpr, pDest->affinity);
r1 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp4(v, OP_MakeRecord, pIn->iMem, 1, r1, &p->affinity, 1);
sqlite3ExprCacheAffinityChange(pParse, pIn->iMem, 1);
sqlite3VdbeAddOp2(v, OP_IdxInsert, pDest->iParm, r1);
sqlite3ReleaseTempReg(pParse, r1);
break;
}
#if 0 /* Never occurs on an ORDER BY query */
/* If any row exist in the result set, record that fact and abort.
*/
case SRT_Exists: {
sqlite3VdbeAddOp2(v, OP_Integer, 1, pDest->iParm);
/* The LIMIT clause will terminate the loop for us */
break;
}
#endif
/* If this is a scalar select that is part of an expression, then
** store the results in the appropriate memory cell and break out
** of the scan loop.
*/
case SRT_Mem: {
assert( pIn->nMem==1 );
sqlite3ExprCodeMove(pParse, pIn->iMem, pDest->iParm, 1);
/* The LIMIT clause will jump out of the loop for us */
break;
}
#endif /* #ifndef SQLITE_OMIT_SUBQUERY */
/* Send the data to the callback function or to a subroutine. In the
** case of a subroutine, the subroutine itself is responsible for
** popping the data from the stack.
*/
case SRT_Coroutine: {
if( pDest->iMem==0 ){
pDest->iMem = sqlite3GetTempRange(pParse, pIn->nMem);
pDest->nMem = pIn->nMem;
}
sqlite3ExprCodeMove(pParse, pIn->iMem, pDest->iMem, pDest->nMem);
sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm);
break;
}
case SRT_Callback: {
sqlite3VdbeAddOp2(v, OP_ResultRow, pIn->iMem, pIn->nMem);
sqlite3ExprCacheAffinityChange(pParse, pIn->iMem, pIn->nMem);
break;
}
#if !defined(SQLITE_OMIT_TRIGGER)
/* Discard the results. This is used for SELECT statements inside
** the body of a TRIGGER. The purpose of such selects is to call
** user-defined functions that have side effects. We do not care
** about the actual results of the select.
*/
default: {
break;
}
#endif
}
/* Jump to the end of the loop if the LIMIT is reached.
*/
if( p->iLimit ){
sqlite3VdbeAddOp2(v, OP_AddImm, p->iLimit, -1);
sqlite3VdbeAddOp2(v, OP_IfZero, p->iLimit, iBreak);
}
/* Generate the subroutine return
*/
sqlite3VdbeResolveLabel(v, iContinue);
sqlite3VdbeAddOp1(v, OP_Return, regReturn);
return addr;
}
/*
** Alternative compound select code generator for cases when there
** is an ORDER BY clause.
**
** We assume a query of the following form:
**
** <selectA> <operator> <selectB> ORDER BY <orderbylist>
**
** <operator> is one of UNION ALL, UNION, EXCEPT, or INTERSECT. The idea
** is to code both <selectA> and <selectB> with the ORDER BY clause as
** co-routines. Then run the co-routines in parallel and merge the results
** into the output. In addition to the two coroutines (called selectA and
** selectB) there are 7 subroutines:
**
** outA: Move the output of the selectA coroutine into the output
** of the compound query.
**
** outB: Move the output of the selectB coroutine into the output
** of the compound query. (Only generated for UNION and
** UNION ALL. EXCEPT and INSERTSECT never output a row that
** appears only in B.)
**
** AltB: Called when there is data from both coroutines and A<B.
**
** AeqB: Called when there is data from both coroutines and A==B.
**
** AgtB: Called when there is data from both coroutines and A>B.
**
** EofA: Called when data is exhausted from selectA.
**
** EofB: Called when data is exhausted from selectB.
**
** The implementation of the latter five subroutines depend on which
** <operator> is used:
**
**
** UNION ALL UNION EXCEPT INTERSECT
** ------------- ----------------- -------------- -----------------
** AltB: outA, nextA outA, nextA outA, nextA nextA
**
** AeqB: outA, nextA nextA nextA outA, nextA
**
** AgtB: outB, nextB outB, nextB nextB nextB
**
** EofA: outB, nextB outB, nextB halt halt
**
** EofB: outA, nextA outA, nextA outA, nextA halt
**
** In the AltB, AeqB, and AgtB subroutines, an EOF on A following nextA
** causes an immediate jump to EofA and an EOF on B following nextB causes
** an immediate jump to EofB. Within EofA and EofB, and EOF on entry or
** following nextX causes a jump to the end of the select processing.
**
** Duplicate removal in the UNION, EXCEPT, and INTERSECT cases is handled
** within the output subroutine. The regPrev register set holds the previously
** output value. A comparison is made against this value and the output
** is skipped if the next results would be the same as the previous.
**
** The implementation plan is to implement the two coroutines and seven
** subroutines first, then put the control logic at the bottom. Like this:
**
** goto Init
** coA: coroutine for left query (A)
** coB: coroutine for right query (B)
** outA: output one row of A
** outB: output one row of B (UNION and UNION ALL only)
** EofA: ...
** EofB: ...
** AltB: ...
** AeqB: ...
** AgtB: ...
** Init: initialize coroutine registers
** yield coA
** if eof(A) goto EofA
** yield coB
** if eof(B) goto EofB
** Cmpr: Compare A, B
** Jump AltB, AeqB, AgtB
** End: ...
**
** We call AltB, AeqB, AgtB, EofA, and EofB "subroutines" but they are not
** actually called using Gosub and they do not Return. EofA and EofB loop
** until all data is exhausted then jump to the "end" labe. AltB, AeqB,
** and AgtB jump to either L2 or to one of EofA or EofB.
*/
#ifndef SQLITE_OMIT_COMPOUND_SELECT
static int multiSelectOrderBy(
Parse *pParse, /* Parsing context */
Select *p, /* The right-most of SELECTs to be coded */
SelectDest *pDest /* What to do with query results */
){
int i, j; /* Loop counters */
Select *pPrior; /* Another SELECT immediately to our left */
Vdbe *v; /* Generate code to this VDBE */
SelectDest destA; /* Destination for coroutine A */
SelectDest destB; /* Destination for coroutine B */
int regAddrA; /* Address register for select-A coroutine */
int regEofA; /* Flag to indicate when select-A is complete */
int regAddrB; /* Address register for select-B coroutine */
int regEofB; /* Flag to indicate when select-B is complete */
int addrSelectA; /* Address of the select-A coroutine */
int addrSelectB; /* Address of the select-B coroutine */
int regOutA; /* Address register for the output-A subroutine */
int regOutB; /* Address register for the output-B subroutine */
int addrOutA; /* Address of the output-A subroutine */
int addrOutB; /* Address of the output-B subroutine */
int addrEofA; /* Address of the select-A-exhausted subroutine */
int addrEofB; /* Address of the select-B-exhausted subroutine */
int addrAltB; /* Address of the A<B subroutine */
int addrAeqB; /* Address of the A==B subroutine */
int addrAgtB; /* Address of the A>B subroutine */
int regLimitA; /* Limit register for select-A */
int regLimitB; /* Limit register for select-A */
int regPrev; /* A range of registers to hold previous output */
int savedLimit; /* Saved value of p->iLimit */
int savedOffset; /* Saved value of p->iOffset */
int labelCmpr; /* Label for the start of the merge algorithm */
int labelEnd; /* Label for the end of the overall SELECT stmt */
int j1; /* Jump instructions that get retargetted */
int op; /* One of TK_ALL, TK_UNION, TK_EXCEPT, TK_INTERSECT */
KeyInfo *pKeyDup; /* Comparison information for duplicate removal */
KeyInfo *pKeyMerge; /* Comparison information for merging rows */
sqlite3 *db; /* Database connection */
ExprList *pOrderBy; /* The ORDER BY clause */
int nOrderBy; /* Number of terms in the ORDER BY clause */
int *aPermute; /* Mapping from ORDER BY terms to result set columns */
u8 NotUsed; /* Dummy variables */
assert( p->pOrderBy!=0 );
db = pParse->db;
v = pParse->pVdbe;
if( v==0 ) return SQLITE_NOMEM;
labelEnd = sqlite3VdbeMakeLabel(v);
labelCmpr = sqlite3VdbeMakeLabel(v);
/* Patch up the ORDER BY clause
*/
op = p->op;
pPrior = p->pPrior;
assert( pPrior->pOrderBy==0 );
pOrderBy = p->pOrderBy;
assert( pOrderBy );
if( processCompoundOrderBy(pParse, p) ){
return SQLITE_ERROR;
}
nOrderBy = pOrderBy->nExpr;
/* For operators other than UNION ALL we have to make sure that
** the ORDER BY clause covers every term of the result set. Add
** terms to the ORDER BY clause as necessary.
*/
if( op!=TK_ALL ){
for(i=1; db->mallocFailed==0 && i<=p->pEList->nExpr; i++){
for(j=0; j<nOrderBy; j++){
Expr *pTerm = pOrderBy->a[j].pExpr;
assert( pTerm->op==TK_INTEGER );
assert( (pTerm->flags & EP_IntValue)!=0 );
if( pTerm->iTable==i ) break;
}
if( j==nOrderBy ){
Expr *pNew = sqlite3PExpr(pParse, TK_INTEGER, 0, 0, 0);
if( pNew==0 ) return SQLITE_NOMEM;
pNew->flags |= EP_IntValue;
pNew->iTable = i;
pOrderBy = sqlite3ExprListAppend(pParse, pOrderBy, pNew, 0);
nOrderBy++;
}
}
}
/* Compute the comparison permutation and keyinfo that is used with
** the permutation in order to comparisons to determine if the next
** row of results comes from selectA or selectB. Also add explicit
** collations to the ORDER BY clause terms so that when the subqueries
** to the right and the left are evaluated, they use the correct
** collation.
*/
aPermute = sqlite3DbMallocRaw(db, sizeof(int)*nOrderBy);
if( aPermute ){
for(i=0; i<nOrderBy; i++){
Expr *pTerm = pOrderBy->a[i].pExpr;
assert( pTerm->op==TK_INTEGER );
assert( (pTerm->flags & EP_IntValue)!=0 );
aPermute[i] = pTerm->iTable-1;
assert( aPermute[i]>=0 && aPermute[i]<p->pEList->nExpr );
}
pKeyMerge =
sqlite3DbMallocRaw(db, sizeof(*pKeyMerge)+nOrderBy*(sizeof(CollSeq*)+1));
if( pKeyMerge ){
pKeyMerge->aSortOrder = (u8*)&pKeyMerge->aColl[nOrderBy];
pKeyMerge->nField = nOrderBy;
pKeyMerge->enc = ENC(db);
for(i=0; i<nOrderBy; i++){
CollSeq *pColl;
Expr *pTerm = pOrderBy->a[i].pExpr;
if( pTerm->flags & EP_ExpCollate ){
pColl = pTerm->pColl;
}else{
pColl = multiSelectCollSeq(pParse, p, aPermute[i]);
pTerm->flags |= EP_ExpCollate;
pTerm->pColl = pColl;
}
pKeyMerge->aColl[i] = pColl;
pKeyMerge->aSortOrder[i] = pOrderBy->a[i].sortOrder;
}
}
}else{
pKeyMerge = 0;
}
/* Reattach the ORDER BY clause to the query.
*/
p->pOrderBy = pOrderBy;
pPrior->pOrderBy = sqlite3ExprListDup(pParse->db, pOrderBy);
/* Allocate a range of temporary registers and the KeyInfo needed
** for the logic that removes duplicate result rows when the
** operator is UNION, EXCEPT, or INTERSECT (but not UNION ALL).
*/
if( op==TK_ALL ){
regPrev = 0;
}else{
int nExpr = p->pEList->nExpr;
assert( nOrderBy>=nExpr );
regPrev = sqlite3GetTempRange(pParse, nExpr+1);
sqlite3VdbeAddOp2(v, OP_Integer, 0, regPrev);
pKeyDup = sqlite3DbMallocZero(db,
sizeof(*pKeyDup) + nExpr*(sizeof(CollSeq*)+1) );
if( pKeyDup ){
pKeyDup->aSortOrder = (u8*)&pKeyDup->aColl[nExpr];
pKeyDup->nField = nExpr;
pKeyDup->enc = ENC(db);
for(i=0; i<nExpr; i++){
pKeyDup->aColl[i] = multiSelectCollSeq(pParse, p, i);
pKeyDup->aSortOrder[i] = 0;
}
}
}
/* Separate the left and the right query from one another
*/
p->pPrior = 0;
pPrior->pRightmost = 0;
processOrderGroupBy(pParse, p, p->pOrderBy, 1, &NotUsed);
if( pPrior->pPrior==0 ){
processOrderGroupBy(pParse, pPrior, pPrior->pOrderBy, 1, &NotUsed);
}
/* Compute the limit registers */
computeLimitRegisters(pParse, p, labelEnd);
if( p->iLimit && op==TK_ALL ){
regLimitA = ++pParse->nMem;
regLimitB = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Copy, p->iOffset ? p->iOffset+1 : p->iLimit,
regLimitA);
sqlite3VdbeAddOp2(v, OP_Copy, regLimitA, regLimitB);
}else{
regLimitA = regLimitB = 0;
}
sqlite3ExprDelete(db, p->pLimit);
p->pLimit = 0;
sqlite3ExprDelete(db, p->pOffset);
p->pOffset = 0;
regAddrA = ++pParse->nMem;
regEofA = ++pParse->nMem;
regAddrB = ++pParse->nMem;
regEofB = ++pParse->nMem;
regOutA = ++pParse->nMem;
regOutB = ++pParse->nMem;
sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA);
sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB);
/* Jump past the various subroutines and coroutines to the main
** merge loop
*/
j1 = sqlite3VdbeAddOp0(v, OP_Goto);
addrSelectA = sqlite3VdbeCurrentAddr(v);
/* Generate a coroutine to evaluate the SELECT statement to the
** left of the compound operator - the "A" select.
*/
VdbeNoopComment((v, "Begin coroutine for left SELECT"));
pPrior->iLimit = regLimitA;
sqlite3Select(pParse, pPrior, &destA, 0, 0, 0);
sqlite3VdbeAddOp2(v, OP_Integer, 1, regEofA);
sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
VdbeNoopComment((v, "End coroutine for left SELECT"));
/* Generate a coroutine to evaluate the SELECT statement on
** the right - the "B" select
*/
addrSelectB = sqlite3VdbeCurrentAddr(v);
VdbeNoopComment((v, "Begin coroutine for right SELECT"));
savedLimit = p->iLimit;
savedOffset = p->iOffset;
p->iLimit = regLimitB;
p->iOffset = 0;
sqlite3Select(pParse, p, &destB, 0, 0, 0);
p->iLimit = savedLimit;
p->iOffset = savedOffset;
sqlite3VdbeAddOp2(v, OP_Integer, 1, regEofB);
sqlite3VdbeAddOp1(v, OP_Yield, regAddrB);
VdbeNoopComment((v, "End coroutine for right SELECT"));
/* Generate a subroutine that outputs the current row of the A
** select as the next output row of the compound select.
*/
VdbeNoopComment((v, "Output routine for A"));
addrOutA = generateOutputSubroutine(pParse,
p, &destA, pDest, regOutA,
regPrev, pKeyDup, P4_KEYINFO_HANDOFF, labelEnd);
/* Generate a subroutine that outputs the current row of the B
** select as the next output row of the compound select.
*/
if( op==TK_ALL || op==TK_UNION ){
VdbeNoopComment((v, "Output routine for B"));
addrOutB = generateOutputSubroutine(pParse,
p, &destB, pDest, regOutB,
regPrev, pKeyDup, P4_KEYINFO_STATIC, labelEnd);
}
/* Generate a subroutine to run when the results from select A
** are exhausted and only data in select B remains.
*/
VdbeNoopComment((v, "eof-A subroutine"));
if( op==TK_EXCEPT || op==TK_INTERSECT ){
addrEofA = sqlite3VdbeAddOp2(v, OP_Goto, 0, labelEnd);
}else{
addrEofA = sqlite3VdbeAddOp2(v, OP_If, regEofB, labelEnd);
sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
sqlite3VdbeAddOp1(v, OP_Yield, regAddrB);
sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEofA);
}
/* Generate a subroutine to run when the results from select B
** are exhausted and only data in select A remains.
*/
if( op==TK_INTERSECT ){
addrEofB = addrEofA;
}else{
VdbeNoopComment((v, "eof-B subroutine"));
addrEofB = sqlite3VdbeAddOp2(v, OP_If, regEofA, labelEnd);
sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEofB);
}
/* Generate code to handle the case of A<B
*/
VdbeNoopComment((v, "A-lt-B subroutine"));
addrAltB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA);
sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);
/* Generate code to handle the case of A==B
*/
if( op==TK_ALL ){
addrAeqB = addrAltB;
}else if( op==TK_INTERSECT ){
addrAeqB = addrAltB;
addrAltB++;
}else{
VdbeNoopComment((v, "A-eq-B subroutine"));
addrAeqB =
sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA);
sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);
}
/* Generate code to handle the case of A>B
*/
VdbeNoopComment((v, "A-gt-B subroutine"));
addrAgtB = sqlite3VdbeCurrentAddr(v);
if( op==TK_ALL || op==TK_UNION ){
sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
}
sqlite3VdbeAddOp1(v, OP_Yield, regAddrB);
sqlite3VdbeAddOp2(v, OP_If, regEofB, addrEofB);
sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);
/* This code runs once to initialize everything.
*/
sqlite3VdbeJumpHere(v, j1);
sqlite3VdbeAddOp2(v, OP_Integer, 0, regEofA);
sqlite3VdbeAddOp2(v, OP_Integer, 0, regEofB);
sqlite3VdbeAddOp2(v, OP_Gosub, regAddrA, addrSelectA);
sqlite3VdbeAddOp2(v, OP_Gosub, regAddrB, addrSelectB);
sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA);
sqlite3VdbeAddOp2(v, OP_If, regEofB, addrEofB);
/* Implement the main merge loop
*/
sqlite3VdbeResolveLabel(v, labelCmpr);
sqlite3VdbeAddOp4(v, OP_Permutation, 0, 0, 0, (char*)aPermute, P4_INTARRAY);
sqlite3VdbeAddOp4(v, OP_Compare, destA.iMem, destB.iMem, nOrderBy,
(char*)pKeyMerge, P4_KEYINFO_HANDOFF);
sqlite3VdbeAddOp3(v, OP_Jump, addrAltB, addrAeqB, addrAgtB);
/* Release temporary registers
*/
if( regPrev ){
sqlite3ReleaseTempRange(pParse, regPrev, nOrderBy+1);
}
/* Jump to the this point in order to terminate the query.
*/
sqlite3VdbeResolveLabel(v, labelEnd);
/* Set the number of output columns
*/
if( pDest->eDest==SRT_Callback ){
Select *pFirst = pPrior;
while( pFirst->pPrior ) pFirst = pFirst->pPrior;
generateColumnNames(pParse, 0, pFirst->pEList);
}
/* Reassembly the compound query so that it will be freed correctly
** by the calling function */
if( p->pPrior ){
sqlite3SelectDelete(db, p->pPrior);
}
p->pPrior = pPrior;
/*** TBD: Insert subroutine calls to close cursors on incomplete
**** subqueries ****/
return SQLITE_OK;
}
#endif
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/* Forward Declarations */
static void substExprList(sqlite3*, ExprList*, int, ExprList*);
static void substSelect(sqlite3*, Select *, int, ExprList *);
/*
** Scan through the expression pExpr. Replace every reference to
** a column in table number iTable with a copy of the iColumn-th
** entry in pEList. (But leave references to the ROWID column
** unchanged.)
**
** This routine is part of the flattening procedure. A subquery
** whose result set is defined by pEList appears as entry in the
** FROM clause of a SELECT such that the VDBE cursor assigned to that
** FORM clause entry is iTable. This routine make the necessary
** changes to pExpr so that it refers directly to the source table
** of the subquery rather the result set of the subquery.
*/
static void substExpr(
sqlite3 *db, /* Report malloc errors to this connection */
Expr *pExpr, /* Expr in which substitution occurs */
int iTable, /* Table to be substituted */
ExprList *pEList /* Substitute expressions */
){
if( pExpr==0 ) return;
if( pExpr->op==TK_COLUMN && pExpr->iTable==iTable ){
if( pExpr->iColumn<0 ){
pExpr->op = TK_NULL;
}else{
Expr *pNew;
assert( pEList!=0 && pExpr->iColumn<pEList->nExpr );
assert( pExpr->pLeft==0 && pExpr->pRight==0 && pExpr->pList==0 );
pNew = pEList->a[pExpr->iColumn].pExpr;
assert( pNew!=0 );
pExpr->op = pNew->op;
assert( pExpr->pLeft==0 );
pExpr->pLeft = sqlite3ExprDup(db, pNew->pLeft);
assert( pExpr->pRight==0 );
pExpr->pRight = sqlite3ExprDup(db, pNew->pRight);
assert( pExpr->pList==0 );
pExpr->pList = sqlite3ExprListDup(db, pNew->pList);
pExpr->iTable = pNew->iTable;
pExpr->pTab = pNew->pTab;
pExpr->iColumn = pNew->iColumn;
pExpr->iAgg = pNew->iAgg;
sqlite3TokenCopy(db, &pExpr->token, &pNew->token);
sqlite3TokenCopy(db, &pExpr->span, &pNew->span);
pExpr->pSelect = sqlite3SelectDup(db, pNew->pSelect);
pExpr->flags = pNew->flags;
}
}else{
substExpr(db, pExpr->pLeft, iTable, pEList);
substExpr(db, pExpr->pRight, iTable, pEList);
substSelect(db, pExpr->pSelect, iTable, pEList);
substExprList(db, pExpr->pList, iTable, pEList);
}
}
static void substExprList(
sqlite3 *db, /* Report malloc errors here */
ExprList *pList, /* List to scan and in which to make substitutes */
int iTable, /* Table to be substituted */
ExprList *pEList /* Substitute values */
){
int i;
if( pList==0 ) return;
for(i=0; i<pList->nExpr; i++){
substExpr(db, pList->a[i].pExpr, iTable, pEList);
}
}
static void substSelect(
sqlite3 *db, /* Report malloc errors here */
Select *p, /* SELECT statement in which to make substitutions */
int iTable, /* Table to be replaced */
ExprList *pEList /* Substitute values */
){
if( !p ) return;
substExprList(db, p->pEList, iTable, pEList);
substExprList(db, p->pGroupBy, iTable, pEList);
substExprList(db, p->pOrderBy, iTable, pEList);
substExpr(db, p->pHaving, iTable, pEList);
substExpr(db, p->pWhere, iTable, pEList);
substSelect(db, p->pPrior, iTable, pEList);
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
/*
** This routine attempts to flatten subqueries in order to speed
** execution. It returns 1 if it makes changes and 0 if no flattening
** occurs.
**
** To understand the concept of flattening, consider the following
** query:
**
** SELECT a FROM (SELECT x+y AS a FROM t1 WHERE z<100) WHERE a>5
**
** The default way of implementing this query is to execute the
** subquery first and store the results in a temporary table, then
** run the outer query on that temporary table. This requires two
** passes over the data. Furthermore, because the temporary table
** has no indices, the WHERE clause on the outer query cannot be
** optimized.
**
** This routine attempts to rewrite queries such as the above into
** a single flat select, like this:
**
** SELECT x+y AS a FROM t1 WHERE z<100 AND a>5
**
** The code generated for this simpification gives the same result
** but only has to scan the data once. And because indices might
** exist on the table t1, a complete scan of the data might be
** avoided.
**
** Flattening is only attempted if all of the following are true:
**
** (1) The subquery and the outer query do not both use aggregates.
**
** (2) The subquery is not an aggregate or the outer query is not a join.
**
** (3) The subquery is not the right operand of a left outer join, or
** the subquery is not itself a join. (Ticket #306)
**
** (4) The subquery is not DISTINCT or the outer query is not a join.
**
** (5) The subquery is not DISTINCT or the outer query does not use
** aggregates.
**
** (6) The subquery does not use aggregates or the outer query is not
** DISTINCT.
**
** (7) The subquery has a FROM clause.
**
** (8) The subquery does not use LIMIT or the outer query is not a join.
**
** (9) The subquery does not use LIMIT or the outer query does not use
** aggregates.
**
** (10) The subquery does not use aggregates or the outer query does not
** use LIMIT.
**
** (11) The subquery and the outer query do not both have ORDER BY clauses.
**
** (12) The subquery is not the right term of a LEFT OUTER JOIN or the
** subquery has no WHERE clause. (added by ticket #350)
**
** (13) The subquery and outer query do not both use LIMIT
**
** (14) The subquery does not use OFFSET
**
** (15) The outer query is not part of a compound select or the
** subquery does not have both an ORDER BY and a LIMIT clause.
** (See ticket #2339)
**
** (16) The outer query is not an aggregate or the subquery does
** not contain ORDER BY. (Ticket #2942) This used to not matter
** until we introduced the group_concat() function.
**
** (17) The sub-query is not a compound select, or it is a UNION ALL
** compound clause made up entirely of non-aggregate queries, and
** the parent query:
**
** * is not itself part of a compound select,
** * is not an aggregate or DISTINCT query, and
** * has no other tables or sub-selects in the FROM clause.
**
** The parent and sub-query may contain WHERE clauses. Subject to
** rules (11), (13) and (14), they may also contain ORDER BY,
** LIMIT and OFFSET clauses.
**
** (18) If the sub-query is a compound select, then all terms of the
** ORDER by clause of the parent must be simple references to
** columns of the sub-query.
**
** In this routine, the "p" parameter is a pointer to the outer query.
** The subquery is p->pSrc->a[iFrom]. isAgg is true if the outer query
** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
**
** If flattening is not attempted, this routine is a no-op and returns 0.
** If flattening is attempted this routine returns 1.
**
** All of the expression analysis must occur on both the outer query and
** the subquery before this routine runs.
*/
static int flattenSubquery(
Parse *pParse, /* Parsing context */
Select *p, /* The parent or outer SELECT statement */
int iFrom, /* Index in p->pSrc->a[] of the inner subquery */
int isAgg, /* True if outer SELECT uses aggregate functions */
int subqueryIsAgg /* True if the subquery uses aggregate functions */
){
const char *zSavedAuthContext = pParse->zAuthContext;
Select *pParent;
Select *pSub; /* The inner query or "subquery" */
Select *pSub1; /* Pointer to the rightmost select in sub-query */
SrcList *pSrc; /* The FROM clause of the outer query */
SrcList *pSubSrc; /* The FROM clause of the subquery */
ExprList *pList; /* The result set of the outer query */
int iParent; /* VDBE cursor number of the pSub result set temp table */
int i; /* Loop counter */
Expr *pWhere; /* The WHERE clause */
struct SrcList_item *pSubitem; /* The subquery */
sqlite3 *db = pParse->db;
/* Check to see if flattening is permitted. Return 0 if not.
*/
if( p==0 ) return 0;
pSrc = p->pSrc;
assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc );
pSubitem = &pSrc->a[iFrom];
iParent = pSubitem->iCursor;
pSub = pSubitem->pSelect;
assert( pSub!=0 );
if( isAgg && subqueryIsAgg ) return 0; /* Restriction (1) */
if( subqueryIsAgg && pSrc->nSrc>1 ) return 0; /* Restriction (2) */
pSubSrc = pSub->pSrc;
assert( pSubSrc );
/* Prior to version 3.1.2, when LIMIT and OFFSET had to be simple constants,
** not arbitrary expresssions, we allowed some combining of LIMIT and OFFSET
** because they could be computed at compile-time. But when LIMIT and OFFSET
** became arbitrary expressions, we were forced to add restrictions (13)
** and (14). */
if( pSub->pLimit && p->pLimit ) return 0; /* Restriction (13) */
if( pSub->pOffset ) return 0; /* Restriction (14) */
if( p->pRightmost && pSub->pLimit && pSub->pOrderBy ){
return 0; /* Restriction (15) */
}
if( pSubSrc->nSrc==0 ) return 0; /* Restriction (7) */
if( (pSub->isDistinct || pSub->pLimit)
&& (pSrc->nSrc>1 || isAgg) ){ /* Restrictions (4)(5)(8)(9) */
return 0;
}
if( p->isDistinct && subqueryIsAgg ) return 0; /* Restriction (6) */
if( (p->disallowOrderBy || p->pOrderBy) && pSub->pOrderBy ){
return 0; /* Restriction (11) */
}
if( isAgg && pSub->pOrderBy ) return 0; /* Restriction (16) */
/* Restriction 3: If the subquery is a join, make sure the subquery is
** not used as the right operand of an outer join. Examples of why this
** is not allowed:
**
** t1 LEFT OUTER JOIN (t2 JOIN t3)
**
** If we flatten the above, we would get
**
** (t1 LEFT OUTER JOIN t2) JOIN t3
**
** which is not at all the same thing.
*/
if( pSubSrc->nSrc>1 && (pSubitem->jointype & JT_OUTER)!=0 ){
return 0;
}
/* Restriction 12: If the subquery is the right operand of a left outer
** join, make sure the subquery has no WHERE clause.
** An examples of why this is not allowed:
**
** t1 LEFT OUTER JOIN (SELECT * FROM t2 WHERE t2.x>0)
**
** If we flatten the above, we would get
**
** (t1 LEFT OUTER JOIN t2) WHERE t2.x>0
**
** But the t2.x>0 test will always fail on a NULL row of t2, which
** effectively converts the OUTER JOIN into an INNER JOIN.
*/
if( (pSubitem->jointype & JT_OUTER)!=0 && pSub->pWhere!=0 ){
return 0;
}
/* Restriction 17: If the sub-query is a compound SELECT, then it must
** use only the UNION ALL operator. And none of the simple select queries
** that make up the compound SELECT are allowed to be aggregate or distinct
** queries.
*/
if( pSub->pPrior ){
if( p->pPrior || isAgg || p->isDistinct || pSrc->nSrc!=1 ){
return 0;
}
for(pSub1=pSub; pSub1; pSub1=pSub1->pPrior){
if( pSub1->isAgg || pSub1->isDistinct
|| (pSub1->pPrior && pSub1->op!=TK_ALL)
|| !pSub1->pSrc || pSub1->pSrc->nSrc!=1
){
return 0;
}
}
/* Restriction 18. */
if( p->pOrderBy ){
int ii;
for(ii=0; ii<p->pOrderBy->nExpr; ii++){
Expr *pExpr = p->pOrderBy->a[ii].pExpr;
if( pExpr->op!=TK_COLUMN || pExpr->iTable!=iParent ){
return 0;
}
}
}
}
pParse->zAuthContext = pSubitem->zName;
sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0);
pParse->zAuthContext = zSavedAuthContext;
/* If the sub-query is a compound SELECT statement, then it must be
** a UNION ALL and the parent query must be of the form:
**
** SELECT <expr-list> FROM (<sub-query>) <where-clause>
**
** followed by any ORDER BY, LIMIT and/or OFFSET clauses. This block
** creates N copies of the parent query without any ORDER BY, LIMIT or
** OFFSET clauses and joins them to the left-hand-side of the original
** using UNION ALL operators. In this case N is the number of simple
** select statements in the compound sub-query.
*/
for(pSub=pSub->pPrior; pSub; pSub=pSub->pPrior){
Select *pNew;
ExprList *pOrderBy = p->pOrderBy;
Expr *pLimit = p->pLimit;
Expr *pOffset = p->pOffset;
Select *pPrior = p->pPrior;
p->pOrderBy = 0;
p->pSrc = 0;
p->pPrior = 0;
p->pLimit = 0;
pNew = sqlite3SelectDup(db, p);
pNew->pPrior = pPrior;
p->pPrior = pNew;
p->pOrderBy = pOrderBy;
p->op = TK_ALL;
p->pSrc = pSrc;
p->pLimit = pLimit;
p->pOffset = pOffset;
p->pRightmost = 0;
pNew->pRightmost = 0;
}
/* If we reach this point, it means flattening is permitted for the
** iFrom-th entry of the FROM clause in the outer query.
*/
pSub = pSub1 = pSubitem->pSelect;
for(pParent=p; pParent; pParent=pParent->pPrior, pSub=pSub->pPrior){
int nSubSrc = pSubSrc->nSrc;
int jointype = 0;
pSubSrc = pSub->pSrc;
pSrc = pParent->pSrc;
/* Move all of the FROM elements of the subquery into the
** the FROM clause of the outer query. Before doing this, remember
** the cursor number for the original outer query FROM element in
** iParent. The iParent cursor will never be used. Subsequent code
** will scan expressions looking for iParent references and replace
** those references with expressions that resolve to the subquery FROM
** elements we are now copying in.
*/
if( pSrc ){
pSubitem = &pSrc->a[iFrom];
nSubSrc = pSubSrc->nSrc;
jointype = pSubitem->jointype;
sqlite3DeleteTable(pSubitem->pTab);
sqlite3DbFree(db, pSubitem->zDatabase);
sqlite3DbFree(db, pSubitem->zName);
sqlite3DbFree(db, pSubitem->zAlias);
pSubitem->pTab = 0;
pSubitem->zDatabase = 0;
pSubitem->zName = 0;
pSubitem->zAlias = 0;
}
if( nSubSrc!=1 || !pSrc ){
int extra = nSubSrc - 1;
for(i=(pSrc?1:0); i<nSubSrc; i++){
pSrc = sqlite3SrcListAppend(db, pSrc, 0, 0);
if( pSrc==0 ){
pParent->pSrc = 0;
return 1;
}
}
pParent->pSrc = pSrc;
for(i=pSrc->nSrc-1; i-extra>=iFrom; i--){
pSrc->a[i] = pSrc->a[i-extra];
}
}
for(i=0; i<nSubSrc; i++){
pSrc->a[i+iFrom] = pSubSrc->a[i];
memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i]));
}
pSrc->a[iFrom].jointype = jointype;
/* Now begin substituting subquery result set expressions for
** references to the iParent in the outer query.
**
** Example:
**
** SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b;
** \ \_____________ subquery __________/ /
** \_____________________ outer query ______________________________/
**
** We look at every expression in the outer query and every place we see
** "a" we substitute "x*3" and every place we see "b" we substitute "y+10".
*/
pList = pParent->pEList;
for(i=0; i<pList->nExpr; i++){
Expr *pExpr;
if( pList->a[i].zName==0 && (pExpr = pList->a[i].pExpr)->span.z!=0 ){
pList->a[i].zName =
sqlite3DbStrNDup(db, (char*)pExpr->span.z, pExpr->span.n);
}
}
substExprList(db, pParent->pEList, iParent, pSub->pEList);
if( isAgg ){
substExprList(db, pParent->pGroupBy, iParent, pSub->pEList);
substExpr(db, pParent->pHaving, iParent, pSub->pEList);
}
if( pSub->pOrderBy ){
assert( pParent->pOrderBy==0 );
pParent->pOrderBy = pSub->pOrderBy;
pSub->pOrderBy = 0;
}else if( pParent->pOrderBy ){
substExprList(db, pParent->pOrderBy, iParent, pSub->pEList);
}
if( pSub->pWhere ){
pWhere = sqlite3ExprDup(db, pSub->pWhere);
}else{
pWhere = 0;
}
if( subqueryIsAgg ){
assert( pParent->pHaving==0 );
pParent->pHaving = pParent->pWhere;
pParent->pWhere = pWhere;
substExpr(db, pParent->pHaving, iParent, pSub->pEList);
pParent->pHaving = sqlite3ExprAnd(db, pParent->pHaving,
sqlite3ExprDup(db, pSub->pHaving));
assert( pParent->pGroupBy==0 );
pParent->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy);
}else{
substExpr(db, pParent->pWhere, iParent, pSub->pEList);
pParent->pWhere = sqlite3ExprAnd(db, pParent->pWhere, pWhere);
}
/* The flattened query is distinct if either the inner or the
** outer query is distinct.
*/
pParent->isDistinct = pParent->isDistinct || pSub->isDistinct;
/*
** SELECT ... FROM (SELECT ... LIMIT a OFFSET b) LIMIT x OFFSET y;
**
** One is tempted to try to add a and b to combine the limits. But this
** does not work if either limit is negative.
*/
if( pSub->pLimit ){
pParent->pLimit = pSub->pLimit;
pSub->pLimit = 0;
}
}
/* Finially, delete what is left of the subquery and return
** success.
*/
sqlite3SelectDelete(db, pSub1);
return 1;
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
/*
** Analyze the SELECT statement passed as an argument to see if it
** is a min() or max() query. Return WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX if
** it is, or 0 otherwise. At present, a query is considered to be
** a min()/max() query if:
**
** 1. There is a single object in the FROM clause.
**
** 2. There is a single expression in the result set, and it is
** either min(x) or max(x), where x is a column reference.
*/
static int minMaxQuery(Parse *pParse, Select *p){
Expr *pExpr;
ExprList *pEList = p->pEList;
if( pEList->nExpr!=1 ) return WHERE_ORDERBY_NORMAL;
pExpr = pEList->a[0].pExpr;
pEList = pExpr->pList;
if( pExpr->op!=TK_AGG_FUNCTION || pEList==0 || pEList->nExpr!=1 ) return 0;
if( pEList->a[0].pExpr->op!=TK_AGG_COLUMN ) return WHERE_ORDERBY_NORMAL;
if( pExpr->token.n!=3 ) return WHERE_ORDERBY_NORMAL;
if( sqlite3StrNICmp((char*)pExpr->token.z,"min",3)==0 ){
return WHERE_ORDERBY_MIN;
}else if( sqlite3StrNICmp((char*)pExpr->token.z,"max",3)==0 ){
return WHERE_ORDERBY_MAX;
}
return WHERE_ORDERBY_NORMAL;
}
/*
** This routine resolves any names used in the result set of the
** supplied SELECT statement. If the SELECT statement being resolved
** is a sub-select, then pOuterNC is a pointer to the NameContext
** of the parent SELECT.
*/
int sqlite3SelectResolve(
Parse *pParse, /* The parser context */
Select *p, /* The SELECT statement being coded. */
NameContext *pOuterNC /* The outer name context. May be NULL. */
){
ExprList *pEList; /* Result set. */
int i; /* For-loop variable used in multiple places */
NameContext sNC; /* Local name-context */
ExprList *pGroupBy; /* The group by clause */
/* If this routine has run before, return immediately. */
if( p->isResolved ){
assert( !pOuterNC );
return SQLITE_OK;
}
p->isResolved = 1;
/* If there have already been errors, do nothing. */
if( pParse->nErr>0 ){
return SQLITE_ERROR;
}
/* Prepare the select statement. This call will allocate all cursors
** required to handle the tables and subqueries in the FROM clause.
*/
if( prepSelectStmt(pParse, p) ){
return SQLITE_ERROR;
}
/* Resolve the expressions in the LIMIT and OFFSET clauses. These
** are not allowed to refer to any names, so pass an empty NameContext.
*/
memset(&sNC, 0, sizeof(sNC));
sNC.pParse = pParse;
if( sqlite3ExprResolveNames(&sNC, p->pLimit) ||
sqlite3ExprResolveNames(&sNC, p->pOffset) ){
return SQLITE_ERROR;
}
/* Set up the local name-context to pass to ExprResolveNames() to
** resolve the expression-list.
*/
sNC.allowAgg = 1;
sNC.pSrcList = p->pSrc;
sNC.pNext = pOuterNC;
/* Resolve names in the result set. */
pEList = p->pEList;
if( !pEList ) return SQLITE_ERROR;
for(i=0; i<pEList->nExpr; i++){
Expr *pX = pEList->a[i].pExpr;
if( sqlite3ExprResolveNames(&sNC, pX) ){
return SQLITE_ERROR;
}
}
/* If there are no aggregate functions in the result-set, and no GROUP BY
** expression, do not allow aggregates in any of the other expressions.
*/
assert( !p->isAgg );
pGroupBy = p->pGroupBy;
if( pGroupBy || sNC.hasAgg ){
p->isAgg = 1;
}else{
sNC.allowAgg = 0;
}
/* If a HAVING clause is present, then there must be a GROUP BY clause.
*/
if( p->pHaving && !pGroupBy ){
sqlite3ErrorMsg(pParse, "a GROUP BY clause is required before HAVING");
return SQLITE_ERROR;
}
/* Add the expression list to the name-context before parsing the
** other expressions in the SELECT statement. This is so that
** expressions in the WHERE clause (etc.) can refer to expressions by
** aliases in the result set.
**
** Minor point: If this is the case, then the expression will be
** re-evaluated for each reference to it.
*/
sNC.pEList = p->pEList;
if( sqlite3ExprResolveNames(&sNC, p->pWhere) ||
sqlite3ExprResolveNames(&sNC, p->pHaving) ){
return SQLITE_ERROR;
}
if( p->pPrior==0 ){
if( processOrderGroupBy(pParse, p, p->pOrderBy, 1, &sNC.hasAgg) ){
return SQLITE_ERROR;
}
}
if( processOrderGroupBy(pParse, p, pGroupBy, 0, &sNC.hasAgg) ){
return SQLITE_ERROR;
}
if( pParse->db->mallocFailed ){
return SQLITE_NOMEM;
}
/* Make sure the GROUP BY clause does not contain aggregate functions.
*/
if( pGroupBy ){
struct ExprList_item *pItem;
for(i=0, pItem=pGroupBy->a; i<pGroupBy->nExpr; i++, pItem++){
if( ExprHasProperty(pItem->pExpr, EP_Agg) ){
sqlite3ErrorMsg(pParse, "aggregate functions are not allowed in "
"the GROUP BY clause");
return SQLITE_ERROR;
}
}
}
/* If this is one SELECT of a compound, be sure to resolve names
** in the other SELECTs.
*/
if( p->pPrior ){
return sqlite3SelectResolve(pParse, p->pPrior, pOuterNC);
}else{
return SQLITE_OK;
}
}
/*
** Reset the aggregate accumulator.
**
** The aggregate accumulator is a set of memory cells that hold
** intermediate results while calculating an aggregate. This
** routine simply stores NULLs in all of those memory cells.
*/
static void resetAccumulator(Parse *pParse, AggInfo *pAggInfo){
Vdbe *v = pParse->pVdbe;
int i;
struct AggInfo_func *pFunc;
if( pAggInfo->nFunc+pAggInfo->nColumn==0 ){
return;
}
for(i=0; i<pAggInfo->nColumn; i++){
sqlite3VdbeAddOp2(v, OP_Null, 0, pAggInfo->aCol[i].iMem);
}
for(pFunc=pAggInfo->aFunc, i=0; i<pAggInfo->nFunc; i++, pFunc++){
sqlite3VdbeAddOp2(v, OP_Null, 0, pFunc->iMem);
if( pFunc->iDistinct>=0 ){
Expr *pE = pFunc->pExpr;
if( pE->pList==0 || pE->pList->nExpr!=1 ){
sqlite3ErrorMsg(pParse, "DISTINCT in aggregate must be followed "
"by an expression");
pFunc->iDistinct = -1;
}else{
KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pE->pList);
sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 0,
(char*)pKeyInfo, P4_KEYINFO_HANDOFF);
}
}
}
}
/*
** Invoke the OP_AggFinalize opcode for every aggregate function
** in the AggInfo structure.
*/
static void finalizeAggFunctions(Parse *pParse, AggInfo *pAggInfo){
Vdbe *v = pParse->pVdbe;
int i;
struct AggInfo_func *pF;
for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
ExprList *pList = pF->pExpr->pList;
sqlite3VdbeAddOp4(v, OP_AggFinal, pF->iMem, pList ? pList->nExpr : 0, 0,
(void*)pF->pFunc, P4_FUNCDEF);
}
}
/*
** Update the accumulator memory cells for an aggregate based on
** the current cursor position.
*/
static void updateAccumulator(Parse *pParse, AggInfo *pAggInfo){
Vdbe *v = pParse->pVdbe;
int i;
struct AggInfo_func *pF;
struct AggInfo_col *pC;
pAggInfo->directMode = 1;
for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
int nArg;
int addrNext = 0;
int regAgg;
ExprList *pList = pF->pExpr->pList;
if( pList ){
nArg = pList->nExpr;
regAgg = sqlite3GetTempRange(pParse, nArg);
sqlite3ExprCodeExprList(pParse, pList, regAgg, 0);
}else{
nArg = 0;
regAgg = 0;
}
if( pF->iDistinct>=0 ){
addrNext = sqlite3VdbeMakeLabel(v);
assert( nArg==1 );
codeDistinct(pParse, pF->iDistinct, addrNext, 1, regAgg);
}
if( pF->pFunc->needCollSeq ){
CollSeq *pColl = 0;
struct ExprList_item *pItem;
int j;
assert( pList!=0 ); /* pList!=0 if pF->pFunc->needCollSeq is true */
for(j=0, pItem=pList->a; !pColl && j<nArg; j++, pItem++){
pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
}
if( !pColl ){
pColl = pParse->db->pDfltColl;
}
sqlite3VdbeAddOp4(v, OP_CollSeq, 0, 0, 0, (char *)pColl, P4_COLLSEQ);
}
sqlite3VdbeAddOp4(v, OP_AggStep, 0, regAgg, pF->iMem,
(void*)pF->pFunc, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, nArg);
sqlite3ReleaseTempRange(pParse, regAgg, nArg);
sqlite3ExprCacheAffinityChange(pParse, regAgg, nArg);
if( addrNext ){
sqlite3VdbeResolveLabel(v, addrNext);
}
}
for(i=0, pC=pAggInfo->aCol; i<pAggInfo->nAccumulator; i++, pC++){
sqlite3ExprCode(pParse, pC->pExpr, pC->iMem);
}
pAggInfo->directMode = 0;
}
/*
** Generate code for the given SELECT statement.
**
** The results are distributed in various ways depending on the
** contents of the SelectDest structure pointed to by argument pDest
** as follows:
**
** pDest->eDest Result
** ------------ -------------------------------------------
** SRT_Callback Invoke the callback for each row of the result.
**
** SRT_Mem Store first result in memory cell pDest->iParm
**
** SRT_Set Store results as keys of table pDest->iParm.
** Apply the affinity pDest->affinity before storing them.
**
** SRT_Union Store results as a key in a temporary table pDest->iParm.
**
** SRT_Except Remove results from the temporary table pDest->iParm.
**
** SRT_Table Store results in temporary table pDest->iParm
**
** SRT_EphemTab Create an temporary table pDest->iParm and store
** the result there. The cursor is left open after
** returning.
**
** SRT_Coroutine Invoke a co-routine to compute a single row of
** the result
**
** SRT_Exists Store a 1 in memory cell pDest->iParm if the result
** set is not empty.
**
** SRT_Discard Throw the results away.
**
** See the selectInnerLoop() function for a canonical listing of the
** allowed values of eDest and their meanings.
**
** This routine returns the number of errors. If any errors are
** encountered, then an appropriate error message is left in
** pParse->zErrMsg.
**
** This routine does NOT free the Select structure passed in. The
** calling function needs to do that.
**
** The pParent, parentTab, and *pParentAgg fields are filled in if this
** SELECT is a subquery. This routine may try to combine this SELECT
** with its parent to form a single flat query. In so doing, it might
** change the parent query from a non-aggregate to an aggregate query.
** For that reason, the pParentAgg flag is passed as a pointer, so it
** can be changed.
**
** Example 1: The meaning of the pParent parameter.
**
** SELECT * FROM t1 JOIN (SELECT x, count(*) FROM t2) JOIN t3;
** \ \_______ subquery _______/ /
** \ /
** \____________________ outer query ___________________/
**
** This routine is called for the outer query first. For that call,
** pParent will be NULL. During the processing of the outer query, this
** routine is called recursively to handle the subquery. For the recursive
** call, pParent will point to the outer query. Because the subquery is
** the second element in a three-way join, the parentTab parameter will
** be 1 (the 2nd value of a 0-indexed array.)
*/
int sqlite3Select(
Parse *pParse, /* The parser context */
Select *p, /* The SELECT statement being coded. */
SelectDest *pDest, /* What to do with the query results */
Select *pParent, /* Another SELECT for which this is a sub-query */
int parentTab, /* Index in pParent->pSrc of this query */
int *pParentAgg /* True if pParent uses aggregate functions */
){
int i, j; /* Loop counters */
WhereInfo *pWInfo; /* Return from sqlite3WhereBegin() */
Vdbe *v; /* The virtual machine under construction */
int isAgg; /* True for select lists like "count(*)" */
ExprList *pEList; /* List of columns to extract. */
SrcList *pTabList; /* List of tables to select from */
Expr *pWhere; /* The WHERE clause. May be NULL */
ExprList *pOrderBy; /* The ORDER BY clause. May be NULL */
ExprList *pGroupBy; /* The GROUP BY clause. May be NULL */
Expr *pHaving; /* The HAVING clause. May be NULL */
int isDistinct; /* True if the DISTINCT keyword is present */
int distinct; /* Table to use for the distinct set */
int rc = 1; /* Value to return from this function */
int addrSortIndex; /* Address of an OP_OpenEphemeral instruction */
AggInfo sAggInfo; /* Information used by aggregate queries */
int iEnd; /* Address of the end of the query */
sqlite3 *db; /* The database connection */
db = pParse->db;
if( p==0 || db->mallocFailed || pParse->nErr ){
return 1;
}
if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;
memset(&sAggInfo, 0, sizeof(sAggInfo));
pOrderBy = p->pOrderBy;
if( IgnorableOrderby(pDest) ){
p->pOrderBy = 0;
/* In these cases the DISTINCT operator makes no difference to the
** results, so remove it if it were specified.
*/
assert(pDest->eDest==SRT_Exists || pDest->eDest==SRT_Union ||
pDest->eDest==SRT_Except || pDest->eDest==SRT_Discard);
p->isDistinct = 0;
}
if( sqlite3SelectResolve(pParse, p, 0) ){
goto select_end;
}
p->pOrderBy = pOrderBy;
/* Make local copies of the parameters for this query.
*/
pTabList = p->pSrc;
isAgg = p->isAgg;
pEList = p->pEList;
if( pEList==0 ) goto select_end;
/*
** Do not even attempt to generate any code if we have already seen
** errors before this routine starts.
*/
if( pParse->nErr>0 ) goto select_end;
/* ORDER BY is ignored for some destinations.
*/
if( IgnorableOrderby(pDest) ){
pOrderBy = 0;
}
/* Begin generating code.
*/
v = sqlite3GetVdbe(pParse);
if( v==0 ) goto select_end;
/* Generate code for all sub-queries in the FROM clause
*/
#if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
for(i=0; !p->pPrior && i<pTabList->nSrc; i++){
struct SrcList_item *pItem = &pTabList->a[i];
SelectDest dest;
Select *pSub = pItem->pSelect;
int isAggSub;
char *zName = pItem->zName;
if( pSub==0 || pItem->isPopulated ) continue;
if( zName!=0 ){ /* An sql view */
const char *zSavedAuthContext = pParse->zAuthContext;
pParse->zAuthContext = zName;
rc = sqlite3SelectResolve(pParse, pSub, 0);
pParse->zAuthContext = zSavedAuthContext;
if( rc ){
goto select_end;
}
}
/* Increment Parse.nHeight by the height of the largest expression
** tree refered to by this, the parent select. The child select
** may contain expression trees of at most
** (SQLITE_MAX_EXPR_DEPTH-Parse.nHeight) height. This is a bit
** more conservative than necessary, but much easier than enforcing
** an exact limit.
*/
pParse->nHeight += sqlite3SelectExprHeight(p);
/* Check to see if the subquery can be absorbed into the parent. */
isAggSub = pSub->isAgg;
if( flattenSubquery(pParse, p, i, isAgg, isAggSub) ){
if( isAggSub ){
p->isAgg = isAgg = 1;
}
i = -1;
}else{
sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);
sqlite3Select(pParse, pSub, &dest, p, i, &isAgg);
}
if( pParse->nErr || db->mallocFailed ){
goto select_end;
}
pParse->nHeight -= sqlite3SelectExprHeight(p);
pTabList = p->pSrc;
if( !IgnorableOrderby(pDest) ){
pOrderBy = p->pOrderBy;
}
}
pEList = p->pEList;
#endif
pWhere = p->pWhere;
pGroupBy = p->pGroupBy;
pHaving = p->pHaving;
isDistinct = p->isDistinct;
#ifndef SQLITE_OMIT_COMPOUND_SELECT
/* If there is are a sequence of queries, do the earlier ones first.
*/
if( p->pPrior ){
if( p->pRightmost==0 ){
Select *pLoop, *pRight = 0;
int cnt = 0;
int mxSelect;
for(pLoop=p; pLoop; pLoop=pLoop->pPrior, cnt++){
pLoop->pRightmost = p;
pLoop->pNext = pRight;
pRight = pLoop;
}
mxSelect = db->aLimit[SQLITE_LIMIT_COMPOUND_SELECT];
if( mxSelect && cnt>mxSelect ){
sqlite3ErrorMsg(pParse, "too many terms in compound SELECT");
return 1;
}
}
return multiSelect(pParse, p, pDest);
}
#endif
/* If writing to memory or generating a set
** only a single column may be output.
*/
#ifndef SQLITE_OMIT_SUBQUERY
if( checkForMultiColumnSelectError(pParse, pDest, pEList->nExpr) ){
goto select_end;
}
#endif
/* If possible, rewrite the query to use GROUP BY instead of DISTINCT.
** GROUP BY may use an index, DISTINCT never does.
*/
if( p->isDistinct && !p->isAgg && !p->pGroupBy ){
p->pGroupBy = sqlite3ExprListDup(db, p->pEList);
pGroupBy = p->pGroupBy;
p->isDistinct = 0;
isDistinct = 0;
}
/* If there is an ORDER BY clause, then this sorting
** index might end up being unused if the data can be
** extracted in pre-sorted order. If that is the case, then the
** OP_OpenEphemeral instruction will be changed to an OP_Noop once
** we figure out that the sorting index is not needed. The addrSortIndex
** variable is used to facilitate that change.
*/
if( pOrderBy ){
KeyInfo *pKeyInfo;
pKeyInfo = keyInfoFromExprList(pParse, pOrderBy);
pOrderBy->iECursor = pParse->nTab++;
p->addrOpenEphm[2] = addrSortIndex =
sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
pOrderBy->iECursor, pOrderBy->nExpr+2, 0,
(char*)pKeyInfo, P4_KEYINFO_HANDOFF);
}else{
addrSortIndex = -1;
}
/* If the output is destined for a temporary table, open that table.
*/
if( pDest->eDest==SRT_EphemTab ){
sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pDest->iParm, pEList->nExpr);
}
/* Set the limiter.
*/
iEnd = sqlite3VdbeMakeLabel(v);
computeLimitRegisters(pParse, p, iEnd);
/* Open a virtual index to use for the distinct set.
*/
if( isDistinct ){
KeyInfo *pKeyInfo;
assert( isAgg || pGroupBy );
distinct = pParse->nTab++;
pKeyInfo = keyInfoFromExprList(pParse, p->pEList);
sqlite3VdbeAddOp4(v, OP_OpenEphemeral, distinct, 0, 0,
(char*)pKeyInfo, P4_KEYINFO_HANDOFF);
}else{
distinct = -1;
}
/* Aggregate and non-aggregate queries are handled differently */
if( !isAgg && pGroupBy==0 ){
/* This case is for non-aggregate queries
** Begin the database scan
*/
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pOrderBy, 0);
if( pWInfo==0 ) goto select_end;
/* If sorting index that was created by a prior OP_OpenEphemeral
** instruction ended up not being needed, then change the OP_OpenEphemeral
** into an OP_Noop.
*/
if( addrSortIndex>=0 && pOrderBy==0 ){
sqlite3VdbeChangeToNoop(v, addrSortIndex, 1);
p->addrOpenEphm[2] = -1;
}
/* Use the standard inner loop
*/
assert(!isDistinct);
selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, -1, pDest,
pWInfo->iContinue, pWInfo->iBreak);
/* End the database scan loop.
*/
sqlite3WhereEnd(pWInfo);
}else{
/* This is the processing for aggregate queries */
NameContext sNC; /* Name context for processing aggregate information */
int iAMem; /* First Mem address for storing current GROUP BY */
int iBMem; /* First Mem address for previous GROUP BY */
int iUseFlag; /* Mem address holding flag indicating that at least
** one row of the input to the aggregator has been
** processed */
int iAbortFlag; /* Mem address which causes query abort if positive */
int groupBySort; /* Rows come from source in GROUP BY order */
/* The following variables hold addresses or labels for parts of the
** virtual machine program we are putting together */
int addrOutputRow; /* Start of subroutine that outputs a result row */
int regOutputRow; /* Return address register for output subroutine */
int addrSetAbort; /* Set the abort flag and return */
int addrInitializeLoop; /* Start of code that initializes the input loop */
int addrTopOfLoop; /* Top of the input loop */
int addrEnd; /* End of all processing */
int addrSortingIdx; /* The OP_OpenEphemeral for the sorting index */
int addrReset; /* Subroutine for resetting the accumulator */
int regReset; /* Return address register for reset subroutine */
addrEnd = sqlite3VdbeMakeLabel(v);
/* Convert TK_COLUMN nodes into TK_AGG_COLUMN and make entries in
** sAggInfo for all TK_AGG_FUNCTION nodes in expressions of the
** SELECT statement.
*/
memset(&sNC, 0, sizeof(sNC));
sNC.pParse = pParse;
sNC.pSrcList = pTabList;
sNC.pAggInfo = &sAggInfo;
sAggInfo.nSortingColumn = pGroupBy ? pGroupBy->nExpr+1 : 0;
sAggInfo.pGroupBy = pGroupBy;
sqlite3ExprAnalyzeAggList(&sNC, pEList);
sqlite3ExprAnalyzeAggList(&sNC, pOrderBy);
if( pHaving ){
sqlite3ExprAnalyzeAggregates(&sNC, pHaving);
}
sAggInfo.nAccumulator = sAggInfo.nColumn;
for(i=0; i<sAggInfo.nFunc; i++){
sqlite3ExprAnalyzeAggList(&sNC, sAggInfo.aFunc[i].pExpr->pList);
}
if( db->mallocFailed ) goto select_end;
/* Processing for aggregates with GROUP BY is very different and
** much more complex than aggregates without a GROUP BY.
*/
if( pGroupBy ){
KeyInfo *pKeyInfo; /* Keying information for the group by clause */
int j1;
/* Create labels that we will be needing
*/
addrInitializeLoop = sqlite3VdbeMakeLabel(v);
/* If there is a GROUP BY clause we might need a sorting index to
** implement it. Allocate that sorting index now. If it turns out
** that we do not need it after all, the OpenEphemeral instruction
** will be converted into a Noop.
*/
sAggInfo.sortingIdx = pParse->nTab++;
pKeyInfo = keyInfoFromExprList(pParse, pGroupBy);
addrSortingIdx = sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
sAggInfo.sortingIdx, sAggInfo.nSortingColumn,
0, (char*)pKeyInfo, P4_KEYINFO_HANDOFF);
/* Initialize memory locations used by GROUP BY aggregate processing
*/
iUseFlag = ++pParse->nMem;
iAbortFlag = ++pParse->nMem;
iAMem = pParse->nMem + 1;
pParse->nMem += pGroupBy->nExpr;
iBMem = pParse->nMem + 1;
pParse->nMem += pGroupBy->nExpr;
sqlite3VdbeAddOp2(v, OP_Integer, 0, iAbortFlag);
VdbeComment((v, "clear abort flag"));
sqlite3VdbeAddOp2(v, OP_Integer, 0, iUseFlag);
VdbeComment((v, "indicate accumulator empty"));
sqlite3VdbeAddOp2(v, OP_Goto, 0, addrInitializeLoop);
/* Generate a subroutine that outputs a single row of the result
** set. This subroutine first looks at the iUseFlag. If iUseFlag
** is less than or equal to zero, the subroutine is a no-op. If
** the processing calls for the query to abort, this subroutine
** increments the iAbortFlag memory location before returning in
** order to signal the caller to abort.
*/
addrSetAbort = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp2(v, OP_Integer, 1, iAbortFlag);
VdbeComment((v, "set abort flag"));
regOutputRow = ++pParse->nMem;
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
addrOutputRow = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2);
VdbeComment((v, "Groupby result generator entry point"));
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
finalizeAggFunctions(pParse, &sAggInfo);
if( pHaving ){
sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
}
selectInnerLoop(pParse, p, p->pEList, 0, 0, pOrderBy,
distinct, pDest,
addrOutputRow+1, addrSetAbort);
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
VdbeComment((v, "end groupby result generator"));
/* Generate a subroutine that will reset the group-by accumulator
*/
addrReset = sqlite3VdbeCurrentAddr(v);
regReset = ++pParse->nMem;
resetAccumulator(pParse, &sAggInfo);
sqlite3VdbeAddOp1(v, OP_Return, regReset);
/* Begin a loop that will extract all source rows in GROUP BY order.
** This might involve two separate loops with an OP_Sort in between, or
** it might be a single loop that uses an index to extract information
** in the right order to begin with.
*/
sqlite3VdbeResolveLabel(v, addrInitializeLoop);
sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pGroupBy, 0);
if( pWInfo==0 ) goto select_end;
if( pGroupBy==0 ){
/* The optimizer is able to deliver rows in group by order so
** we do not have to sort. The OP_OpenEphemeral table will be
** cancelled later because we still need to use the pKeyInfo
*/
pGroupBy = p->pGroupBy;
groupBySort = 0;
}else{
/* Rows are coming out in undetermined order. We have to push
** each row into a sorting index, terminate the first loop,
** then loop over the sorting index in order to get the output
** in sorted order
*/
int regBase;
int regRecord;
int nCol;
int nGroupBy;
groupBySort = 1;
nGroupBy = pGroupBy->nExpr;
nCol = nGroupBy + 1;
j = nGroupBy+1;
for(i=0; i<sAggInfo.nColumn; i++){
if( sAggInfo.aCol[i].iSorterColumn>=j ){
nCol++;
j++;
}
}
regBase = sqlite3GetTempRange(pParse, nCol);
sqlite3ExprCodeExprList(pParse, pGroupBy, regBase, 0);
sqlite3VdbeAddOp2(v, OP_Sequence, sAggInfo.sortingIdx,regBase+nGroupBy);
j = nGroupBy+1;
for(i=0; i<sAggInfo.nColumn; i++){
struct AggInfo_col *pCol = &sAggInfo.aCol[i];
if( pCol->iSorterColumn>=j ){
int r1 = j + regBase;
#ifndef NDEBUG
int r2 =
#endif
sqlite3ExprCodeGetColumn(pParse,
pCol->pTab, pCol->iColumn, pCol->iTable, r1, 0);
j++;
/* sAggInfo.aCol[] only contains one entry per column. So
** The reference to pCol->iColumn,pCol->iTable must have been
** the first reference to that column. Hence,
** sqliteExprCodeGetColumn is guaranteed to put the result in
** the column requested.
*/
assert( r1==r2 );
}
}
regRecord = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regRecord);
sqlite3VdbeAddOp2(v, OP_IdxInsert, sAggInfo.sortingIdx, regRecord);
sqlite3ReleaseTempReg(pParse, regRecord);
sqlite3ReleaseTempRange(pParse, regBase, nCol);
sqlite3WhereEnd(pWInfo);
sqlite3VdbeAddOp2(v, OP_Sort, sAggInfo.sortingIdx, addrEnd);
VdbeComment((v, "GROUP BY sort"));
sAggInfo.useSortingIdx = 1;
}
/* Evaluate the current GROUP BY terms and store in b0, b1, b2...
** (b0 is memory location iBMem+0, b1 is iBMem+1, and so forth)
** Then compare the current GROUP BY terms against the GROUP BY terms
** from the previous row currently stored in a0, a1, a2...
*/
addrTopOfLoop = sqlite3VdbeCurrentAddr(v);
for(j=0; j<pGroupBy->nExpr; j++){
if( groupBySort ){
sqlite3VdbeAddOp3(v, OP_Column, sAggInfo.sortingIdx, j, iBMem+j);
}else{
sAggInfo.directMode = 1;
sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr, iBMem+j);
}
}
sqlite3VdbeAddOp4(v, OP_Compare, iAMem, iBMem, pGroupBy->nExpr,
(char*)pKeyInfo, P4_KEYINFO);
j1 = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp3(v, OP_Jump, j1+1, 0, j1+1);
/* Generate code that runs whenever the GROUP BY changes.
** Changes in the GROUP BY are detected by the previous code
** block. If there were no changes, this block is skipped.
**
** This code copies current group by terms in b0,b1,b2,...
** over to a0,a1,a2. It then calls the output subroutine
** and resets the aggregate accumulator registers in preparation
** for the next GROUP BY batch.
*/
sqlite3ExprCodeMove(pParse, iBMem, iAMem, pGroupBy->nExpr);
sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow);
VdbeComment((v, "output one row"));
sqlite3VdbeAddOp2(v, OP_IfPos, iAbortFlag, addrEnd);
VdbeComment((v, "check abort flag"));
sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
VdbeComment((v, "reset accumulator"));
/* Update the aggregate accumulators based on the content of
** the current row
*/
sqlite3VdbeJumpHere(v, j1);
updateAccumulator(pParse, &sAggInfo);
sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag);
VdbeComment((v, "indicate data in accumulator"));
/* End of the loop
*/
if( groupBySort ){
sqlite3VdbeAddOp2(v, OP_Next, sAggInfo.sortingIdx, addrTopOfLoop);
}else{
sqlite3WhereEnd(pWInfo);
sqlite3VdbeChangeToNoop(v, addrSortingIdx, 1);
}
/* Output the final row of result
*/
sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow);
VdbeComment((v, "output final row"));
} /* endif pGroupBy */
else {
ExprList *pMinMax = 0;
ExprList *pDel = 0;
u8 flag;
/* Check if the query is of one of the following forms:
**
** SELECT min(x) FROM ...
** SELECT max(x) FROM ...
**
** If it is, then ask the code in where.c to attempt to sort results
** as if there was an "ORDER ON x" or "ORDER ON x DESC" clause.
** If where.c is able to produce results sorted in this order, then
** add vdbe code to break out of the processing loop after the
** first iteration (since the first iteration of the loop is
** guaranteed to operate on the row with the minimum or maximum
** value of x, the only row required).
**
** A special flag must be passed to sqlite3WhereBegin() to slightly
** modify behaviour as follows:
**
** + If the query is a "SELECT min(x)", then the loop coded by
** where.c should not iterate over any values with a NULL value
** for x.
**
** + The optimizer code in where.c (the thing that decides which
** index or indices to use) should place a different priority on
** satisfying the 'ORDER BY' clause than it does in other cases.
** Refer to code and comments in where.c for details.
*/
flag = minMaxQuery(pParse, p);
if( flag ){
pDel = pMinMax = sqlite3ExprListDup(db, p->pEList->a[0].pExpr->pList);
if( pMinMax && !db->mallocFailed ){
pMinMax->a[0].sortOrder = flag!=WHERE_ORDERBY_MIN;
pMinMax->a[0].pExpr->op = TK_COLUMN;
}
}
/* This case runs if the aggregate has no GROUP BY clause. The
** processing is much simpler since there is only a single row
** of output.
*/
resetAccumulator(pParse, &sAggInfo);
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pMinMax, flag);
if( pWInfo==0 ){
sqlite3ExprListDelete(db, pDel);
goto select_end;
}
updateAccumulator(pParse, &sAggInfo);
if( !pMinMax && flag ){
sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iBreak);
VdbeComment((v, "%s() by index",(flag==WHERE_ORDERBY_MIN?"min":"max")));
}
sqlite3WhereEnd(pWInfo);
finalizeAggFunctions(pParse, &sAggInfo);
pOrderBy = 0;
if( pHaving ){
sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);
}
selectInnerLoop(pParse, p, p->pEList, 0, 0, 0, -1,
pDest, addrEnd, addrEnd);
sqlite3ExprListDelete(db, pDel);
}
sqlite3VdbeResolveLabel(v, addrEnd);
} /* endif aggregate query */
/* If there is an ORDER BY clause, then we need to sort the results
** and send them to the callback one by one.
*/
if( pOrderBy ){
generateSortTail(pParse, p, v, pEList->nExpr, pDest);
}
#ifndef SQLITE_OMIT_SUBQUERY
/* If this was a subquery, we have now converted the subquery into a
** temporary table. So set the SrcList_item.isPopulated flag to prevent
** this subquery from being evaluated again and to force the use of
** the temporary table.
*/
if( pParent ){
assert( pParent->pSrc->nSrc>parentTab );
assert( pParent->pSrc->a[parentTab].pSelect==p );
pParent->pSrc->a[parentTab].isPopulated = 1;
}
#endif
/* Jump here to skip this query
*/
sqlite3VdbeResolveLabel(v, iEnd);
/* The SELECT was successfully coded. Set the return code to 0
** to indicate no errors.
*/
rc = 0;
/* Control jumps to here if an error is encountered above, or upon
** successful coding of the SELECT.
*/
select_end:
/* Identify column names if we will be using them in a callback. This
** step is skipped if the output is going to some other destination.
*/
if( rc==SQLITE_OK && pDest->eDest==SRT_Callback ){
generateColumnNames(pParse, pTabList, pEList);
}
sqlite3DbFree(db, sAggInfo.aCol);
sqlite3DbFree(db, sAggInfo.aFunc);
return rc;
}
#if defined(SQLITE_DEBUG)
/*
*******************************************************************************
** The following code is used for testing and debugging only. The code
** that follows does not appear in normal builds.
**
** These routines are used to print out the content of all or part of a
** parse structures such as Select or Expr. Such printouts are useful
** for helping to understand what is happening inside the code generator
** during the execution of complex SELECT statements.
**
** These routine are not called anywhere from within the normal
** code base. Then are intended to be called from within the debugger
** or from temporary "printf" statements inserted for debugging.
*/
void sqlite3PrintExpr(Expr *p){
if( p->token.z && p->token.n>0 ){
sqlite3DebugPrintf("(%.*s", p->token.n, p->token.z);
}else{
sqlite3DebugPrintf("(%d", p->op);
}
if( p->pLeft ){
sqlite3DebugPrintf(" ");
sqlite3PrintExpr(p->pLeft);
}
if( p->pRight ){
sqlite3DebugPrintf(" ");
sqlite3PrintExpr(p->pRight);
}
sqlite3DebugPrintf(")");
}
void sqlite3PrintExprList(ExprList *pList){
int i;
for(i=0; i<pList->nExpr; i++){
sqlite3PrintExpr(pList->a[i].pExpr);
if( i<pList->nExpr-1 ){
sqlite3DebugPrintf(", ");
}
}
}
void sqlite3PrintSelect(Select *p, int indent){
sqlite3DebugPrintf("%*sSELECT(%p) ", indent, "", p);
sqlite3PrintExprList(p->pEList);
sqlite3DebugPrintf("\n");
if( p->pSrc ){
char *zPrefix;
int i;
zPrefix = "FROM";
for(i=0; i<p->pSrc->nSrc; i++){
struct SrcList_item *pItem = &p->pSrc->a[i];
sqlite3DebugPrintf("%*s ", indent+6, zPrefix);
zPrefix = "";
if( pItem->pSelect ){
sqlite3DebugPrintf("(\n");
sqlite3PrintSelect(pItem->pSelect, indent+10);
sqlite3DebugPrintf("%*s)", indent+8, "");
}else if( pItem->zName ){
sqlite3DebugPrintf("%s", pItem->zName);
}
if( pItem->pTab ){
sqlite3DebugPrintf("(table: %s)", pItem->pTab->zName);
}
if( pItem->zAlias ){
sqlite3DebugPrintf(" AS %s", pItem->zAlias);
}
if( i<p->pSrc->nSrc-1 ){
sqlite3DebugPrintf(",");
}
sqlite3DebugPrintf("\n");
}
}
if( p->pWhere ){
sqlite3DebugPrintf("%*s WHERE ", indent, "");
sqlite3PrintExpr(p->pWhere);
sqlite3DebugPrintf("\n");
}
if( p->pGroupBy ){
sqlite3DebugPrintf("%*s GROUP BY ", indent, "");
sqlite3PrintExprList(p->pGroupBy);
sqlite3DebugPrintf("\n");
}
if( p->pHaving ){
sqlite3DebugPrintf("%*s HAVING ", indent, "");
sqlite3PrintExpr(p->pHaving);
sqlite3DebugPrintf("\n");
}
if( p->pOrderBy ){
sqlite3DebugPrintf("%*s ORDER BY ", indent, "");
sqlite3PrintExprList(p->pOrderBy);
sqlite3DebugPrintf("\n");
}
}
/* End of the structure debug printing code
*****************************************************************************/
#endif /* defined(SQLITE_TEST) || defined(SQLITE_DEBUG) */