FCL/sf/mw/web: comparison webengine/webkitutils/SqliteSymbian/select.c

equal deleted inserted replaced

--1:000000000000
+:dd21522fd290
+/*
+** 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 1.320 2006/08/11 19:08:27 drh Exp $
+*/
+#include "sqliteInt.h"
+/*
+** Delete all the content of a Select structure but do not deallocate
+** the select structure itself.
+*/
+static void clearSelect(Select *p){
+sqlite3ExprListDelete(p->pEList);
+sqlite3SrcListDelete(p->pSrc);
+sqlite3ExprDelete(p->pWhere);
+sqlite3ExprListDelete(p->pGroupBy);
+sqlite3ExprDelete(p->pHaving);
+sqlite3ExprListDelete(p->pOrderBy);
+sqlite3SelectDelete(p->pPrior);
+sqlite3ExprDelete(p->pLimit);
+sqlite3ExprDelete(p->pOffset);
+}
+/*
+** Allocate a new Select structure and return a pointer to that
+** structure.
+*/
+Select *sqlite3SelectNew(
+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;
+pNew = sqliteMalloc( 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(0, sqlite3Expr(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;
+pNew->pLimit = pLimit;
+pNew->pOffset = pOffset;
+pNew->iLimit = -1;
+pNew->iOffset = -1;
+pNew->addrOpenEphm[0] = -1;
+pNew->addrOpenEphm[1] = -1;
+pNew->addrOpenEphm[2] = -1;
+if( pNew==&standin) {
+clearSelect(pNew);
+pNew = 0;
+}
+return pNew;
+}
+/*
+** Delete the given Select structure and all of its substructures.
+*/
+void sqlite3SelectDelete(Select *p){
+if( p ){
+clearSelect(p);
+sqliteFree(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 *zSp1 = " ";
+const char *zSp2 = " ";
+if( pB==0 ){ zSp1++; }
+if( pC==0 ){ zSp2++; }
+sqlite3ErrorMsg(pParse, "unknown or unsupported join type: "
+"%T%s%T%s%T", pA, zSp1, pB, zSp2, 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;
+}
+/*
+** Create an expression node for an identifier with the name of zName
+*/
+Expr *sqlite3CreateIdExpr(const char *zName){
+Token dummy;
+setToken(&dummy, zName);
+return sqlite3Expr(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(
+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 */
+){
+Expr *pE1a, *pE1b, *pE1c;
+Expr *pE2a, *pE2b, *pE2c;
+Expr *pE;
+pE1a = sqlite3CreateIdExpr(zCol);
+pE2a = sqlite3CreateIdExpr(zCol);
+if( zAlias1==0 ){
+zAlias1 = pTab1->zName;
+}
+pE1b = sqlite3CreateIdExpr(zAlias1);
+if( zAlias2==0 ){
+zAlias2 = pTab2->zName;
+}
+pE2b = sqlite3CreateIdExpr(zAlias2);
+pE1c = sqlite3ExprOrFree(TK_DOT, pE1b, pE1a, 0);
+pE2c = sqlite3ExprOrFree(TK_DOT, pE2b, pE2a, 0);
+pE = sqlite3ExprOrFree(TK_EQ, pE1c, pE2c, 0);
+if( pE ){
+ExprSetProperty(pE, EP_FromJoin);
+pE->iRightJoinTable = iRightJoinTable;
+}
+pE = sqlite3ExprAnd(*ppExpr, pE);
+if( pE ){
+*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;
+if( pLeftTab==0 || pRightTab==0 ) continue;
+/* When the NATURAL keyword is present, add WHERE clause terms for
+** every column that the two tables have in common.
+*/
+if( pLeft->jointype & JT_NATURAL ){
+if( pLeft->pOn || pLeft->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(zName, pLeftTab, pLeft->zAlias,
+pRightTab, pRight->zAlias,
+pRight->iCursor, &p->pWhere);
+}
+}
+}
+/* Disallow both ON and USING clauses in the same join
+*/
+if( pLeft->pOn && pLeft->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( pLeft->pOn ){
+setJoinExpr(pLeft->pOn, pRight->iCursor);
+p->pWhere = sqlite3ExprAnd(p->pWhere, pLeft->pOn);
+pLeft->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( pLeft->pUsing ){
+IdList *pList = pLeft->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(zName, pLeftTab, pLeft->zAlias,
+pRightTab, pRight->zAlias,
+pRight->iCursor, &p->pWhere);
+}
+}
+}
+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 */
+){
+Vdbe *v = pParse->pVdbe;
+sqlite3ExprCodeExprList(pParse, pOrderBy);
+sqlite3VdbeAddOp(v, OP_Sequence, pOrderBy->iECursor, 0);
+sqlite3VdbeAddOp(v, OP_Pull, pOrderBy->nExpr + 1, 0);
+sqlite3VdbeAddOp(v, OP_MakeRecord, pOrderBy->nExpr + 2, 0);
+sqlite3VdbeAddOp(v, OP_IdxInsert, pOrderBy->iECursor, 0);
+if( pSelect->iLimit>=0 ){
+int addr1, addr2;
+addr1 = sqlite3VdbeAddOp(v, OP_IfMemZero, pSelect->iLimit+1, 0);
+sqlite3VdbeAddOp(v, OP_MemIncr, -1, pSelect->iLimit+1);
+addr2 = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
+sqlite3VdbeJumpHere(v, addr1);
+sqlite3VdbeAddOp(v, OP_Last, pOrderBy->iECursor, 0);
+sqlite3VdbeAddOp(v, OP_Delete, pOrderBy->iECursor, 0);
+sqlite3VdbeJumpHere(v, addr2);
+pSelect->iLimit = -1;
+}
+}
+/*
+** 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 */
+int nPop          /* Number of times to pop stack when jumping */
+){
+if( p->iOffset>=0 && iContinue!=0 ){
+int addr;
+sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iOffset);
+addr = sqlite3VdbeAddOp(v, OP_IfMemNeg, p->iOffset, 0);
+if( nPop>0 ){
+sqlite3VdbeAddOp(v, OP_Pop, nPop, 0);
+}
+sqlite3VdbeAddOp(v, OP_Goto, 0, iContinue);
+VdbeComment((v, "# skip OFFSET records"));
+sqlite3VdbeJumpHere(v, addr);
+}
+}
+/*
+** Add code that will check to make sure the top N elements of the
+** stack are distinct.  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(
+Vdbe *v,           /* Generate code into this VM */
+int iTab,          /* A sorting index used to test for distinctness */
+int addrRepeat,    /* Jump to here if not distinct */
+int N              /* The top N elements of the stack must be distinct */
+){
+sqlite3VdbeAddOp(v, OP_MakeRecord, -N, 0);
+sqlite3VdbeAddOp(v, OP_Distinct, iTab, sqlite3VdbeCurrentAddr(v)+3);
+sqlite3VdbeAddOp(v, OP_Pop, N+1, 0);
+sqlite3VdbeAddOp(v, OP_Goto, 0, addrRepeat);
+VdbeComment((v, "# skip indistinct records"));
+sqlite3VdbeAddOp(v, OP_IdxInsert, iTab, 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 int 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 */
+int eDest,              /* How to dispose of the results */
+int iParm,              /* An argument to the disposal method */
+int iContinue,          /* Jump here to continue with next row */
+int iBreak,             /* Jump here to break out of the inner loop */
+char *aff               /* affinity string if eDest is SRT_Union */
+){
+Vdbe *v = pParse->pVdbe;
+int i;
+int hasDistinct;        /* True if the DISTINCT keyword is present */
+if( v==0 ) return 0;
+assert( pEList!=0 );
+/* If there was a LIMIT clause on the SELECT statement, then do the check
+** to see if this row should be output.
+*/
+hasDistinct = distinct>=0 && pEList->nExpr>0;
+if( pOrderBy==0 && !hasDistinct ){
+codeOffset(v, p, iContinue, 0);
+}
+/* Pull the requested columns.
+*/
+if( nColumn>0 ){
+for(i=0; i<nColumn; i++){
+sqlite3VdbeAddOp(v, OP_Column, srcTab, i);
+}
+}else{
+nColumn = pEList->nExpr;
+sqlite3ExprCodeExprList(pParse, pEList);
+}
+/* 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(v, distinct, iContinue, nColumn);
+if( pOrderBy==0 ){
+codeOffset(v, p, iContinue, nColumn);
+}
+}
+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: {
+sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
+if( aff ){
+sqlite3VdbeChangeP3(v, -1, aff, P3_STATIC);
+}
+sqlite3VdbeAddOp(v, OP_IdxInsert, iParm, 0);
+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: {
+int addr;
+addr = sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
+sqlite3VdbeChangeP3(v, -1, aff, P3_STATIC);
+sqlite3VdbeAddOp(v, OP_NotFound, iParm, addr+3);
+sqlite3VdbeAddOp(v, OP_Delete, iParm, 0);
+break;
+}
+#endif
+/* Store the result as data using a unique key.
+*/
+case SRT_Table:
+case SRT_EphemTab: {
+sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
+if( pOrderBy ){
+pushOntoSorter(pParse, pOrderBy, p);
+}else{
+sqlite3VdbeAddOp(v, OP_NewRowid, iParm, 0);
+sqlite3VdbeAddOp(v, OP_Pull, 1, 0);
+sqlite3VdbeAddOp(v, OP_Insert, iParm, 0);
+}
+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 addr1 = sqlite3VdbeCurrentAddr(v);
+int addr2;
+assert( nColumn==1 );
+sqlite3VdbeAddOp(v, OP_NotNull, -1, addr1+3);
+sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
+addr2 = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
+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);
+}else{
+char affinity = (iParm>>16)&0xFF;
+affinity = sqlite3CompareAffinity(pEList->a[0].pExpr, affinity);
+sqlite3VdbeOp3(v, OP_MakeRecord, 1, 0, &affinity, 1);
+sqlite3VdbeAddOp(v, OP_IdxInsert, (iParm&0x0000FFFF), 0);
+}
+sqlite3VdbeJumpHere(v, addr2);
+break;
+}
+/* If any row exist in the result set, record that fact and abort.
+*/
+case SRT_Exists: {
+sqlite3VdbeAddOp(v, OP_MemInt, 1, iParm);
+sqlite3VdbeAddOp(v, OP_Pop, nColumn, 0);
+/* 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);
+}else{
+sqlite3VdbeAddOp(v, OP_MemStore, 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_Subroutine:
+case SRT_Callback: {
+if( pOrderBy ){
+sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
+pushOntoSorter(pParse, pOrderBy, p);
+}else if( eDest==SRT_Subroutine ){
+sqlite3VdbeAddOp(v, OP_Gosub, 0, iParm);
+}else{
+sqlite3VdbeAddOp(v, OP_Callback, nColumn, 0);
+}
+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 );
+sqlite3VdbeAddOp(v, OP_Pop, nColumn, 0);
+break;
+}
+#endif
+}
+/* Jump to the end of the loop if the LIMIT is reached.
+*/
+if( p->iLimit>=0 && pOrderBy==0 ){
+sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iLimit);
+sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, iBreak);
+}
+return 0;
+}
+/*
+** 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 P3 field of an opcode using
+** P3_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 = sqliteMalloc( 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 */
+int eDest,       /* Write the sorted results here */
+int iParm        /* Optional parameter associated with eDest */
+){
+int brk = sqlite3VdbeMakeLabel(v);
+int cont = sqlite3VdbeMakeLabel(v);
+int addr;
+int iTab;
+int pseudoTab;
+ExprList *pOrderBy = p->pOrderBy;
+iTab = pOrderBy->iECursor;
+if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
+pseudoTab = pParse->nTab++;
+sqlite3VdbeAddOp(v, OP_OpenPseudo, pseudoTab, 0);
+sqlite3VdbeAddOp(v, OP_SetNumColumns, pseudoTab, nColumn);
+}
+addr = 1 + sqlite3VdbeAddOp(v, OP_Sort, iTab, brk);
+codeOffset(v, p, cont, 0);
+if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
+sqlite3VdbeAddOp(v, OP_Integer, 1, 0);
+}
+sqlite3VdbeAddOp(v, OP_Column, iTab, pOrderBy->nExpr + 1);
+switch( eDest ){
+case SRT_Table:
+case SRT_EphemTab: {
+sqlite3VdbeAddOp(v, OP_NewRowid, iParm, 0);
+sqlite3VdbeAddOp(v, OP_Pull, 1, 0);
+sqlite3VdbeAddOp(v, OP_Insert, iParm, 0);
+break;
+}
+#ifndef SQLITE_OMIT_SUBQUERY
+case SRT_Set: {
+assert( nColumn==1 );
+sqlite3VdbeAddOp(v, OP_NotNull, -1, sqlite3VdbeCurrentAddr(v)+3);
+sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
+sqlite3VdbeAddOp(v, OP_Goto, 0, sqlite3VdbeCurrentAddr(v)+3);
+sqlite3VdbeOp3(v, OP_MakeRecord, 1, 0, "c", P3_STATIC);
+sqlite3VdbeAddOp(v, OP_IdxInsert, (iParm&0x0000FFFF), 0);
+break;
+}
+case SRT_Mem: {
+assert( nColumn==1 );
+sqlite3VdbeAddOp(v, OP_MemStore, iParm, 1);
+/* The LIMIT clause will terminate the loop for us */
+break;
+}
+#endif
+case SRT_Callback:
+case SRT_Subroutine: {
+int i;
+sqlite3VdbeAddOp(v, OP_Insert, pseudoTab, 0);
+for(i=0; i<nColumn; i++){
+sqlite3VdbeAddOp(v, OP_Column, pseudoTab, i);
+}
+if( eDest==SRT_Callback ){
+sqlite3VdbeAddOp(v, OP_Callback, nColumn, 0);
+}else{
+sqlite3VdbeAddOp(v, OP_Gosub, 0, iParm);
+}
+break;
+}
+default: {
+/* Do nothing */
+break;
+}
+}
+/* Jump to the end of the loop when the LIMIT is reached
+*/
+if( p->iLimit>=0 ){
+sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iLimit);
+sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, brk);
+}
+/* The bottom of the loop
+*/
+sqlite3VdbeResolveLabel(v, cont);
+sqlite3VdbeAddOp(v, OP_Next, iTab, addr);
+sqlite3VdbeResolveLabel(v, brk);
+if( eDest==SRT_Callback || eDest==SRT_Subroutine ){
+sqlite3VdbeAddOp(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;
+/* The TK_AS operator can only occur in ORDER BY, GROUP BY, HAVING,
+** and LIMIT clauses.  But pExpr originates in the result set of a
+** SELECT.  So pExpr can never contain an AS operator.
+*/
+assert( pExpr->op!=TK_AS );
+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 */
+){
+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 *zOrigDb = 0;
+const char *zOrigTab = 0;
+const char *zOrigCol = 0;
+const char *zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol);
+/* The vdbe must make it's 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_DECLTYPE, zType, P3_TRANSIENT);
+sqlite3VdbeSetColName(v, i, COLNAME_DATABASE, zOrigDb, P3_TRANSIENT);
+sqlite3VdbeSetColName(v, i, COLNAME_TABLE, zOrigTab, P3_TRANSIENT);
+sqlite3VdbeSetColName(v, i, COLNAME_COLUMN, zOrigCol, P3_TRANSIENT);
+}
+}
+/*
+** 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 || sqlite3MallocFailed() ) 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));
+continue;
+}
+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 && p->span.z && p->span.z[0] ){
+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;
+sqlite3SetString(&zName, zTab, ".", zCol, (char*)0);
+sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, P3_DYNAMIC);
+}else{
+sqlite3VdbeSetColName(v, i, COLNAME_NAME, zCol, strlen(zCol));
+}
+}else if( p->span.z && p->span.z[0] ){
+sqlite3VdbeSetColName(v, i, COLNAME_NAME, (char*)p->span.z, p->span.n);
+/* sqlite3VdbeCompressSpace(v, addr); */
+}else{
+char zName[30];
+assert( p->op!=TK_COLUMN || pTabList==0 );
+sprintf(zName, "column%d", i+1);
+sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, 0);
+}
+}
+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;
+ExprList *pEList;
+Column *aCol, *pCol;
+while( pSelect->pPrior ) pSelect = pSelect->pPrior;
+if( prepSelectStmt(pParse, pSelect) ){
+return 0;
+}
+if( sqlite3SelectResolve(pParse, pSelect, 0) ){
+return 0;
+}
+pTab = sqliteMalloc( sizeof(Table) );
+if( pTab==0 ){
+return 0;
+}
+pTab->nRef = 1;
+pTab->zName = zTabName ? sqliteStrDup(zTabName) : 0;
+pEList = pSelect->pEList;
+pTab->nCol = pEList->nExpr;
+assert( pTab->nCol>0 );
+pTab->aCol = aCol = sqliteMalloc( sizeof(pTab->aCol[0])*pTab->nCol );
+for(i=0, pCol=aCol; i<pTab->nCol; i++, pCol++){
+Expr *p, *pR;
+char *zType;
+char *zName;
+char *zBasename;
+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 = sqliteStrDup(zName);
+}else if( p->op==TK_DOT
+&& (pR=p->pRight)!=0 && pR->token.z && pR->token.z[0] ){
+/* For columns of the from A.B use B as the name */
+zName = sqlite3MPrintf("%T", &pR->token);
+}else if( p->span.z && p->span.z[0] ){
+/* Use the original text of the column expression as its name */
+zName = sqlite3MPrintf("%T", &p->span);
+}else{
+/* If all else fails, make up a name */
+zName = sqlite3MPrintf("column%d", i+1);
+}
+sqlite3Dequote(zName);
+if( sqlite3MallocFailed() ){
+sqliteFree(zName);
+sqlite3DeleteTable(0, pTab);
+return 0;
+}
+/* Make sure the column name is unique.  If the name is not unique,
+** append a integer to the name so that it becomes unique.
+*/
+zBasename = zName;
+for(j=cnt=0; j<i; j++){
+if( sqlite3StrICmp(aCol[j].zName, zName)==0 ){
+zName = sqlite3MPrintf("%s:%d", zBasename, ++cnt);
+j = -1;
+if( zName==0 ) break;
+}
+}
+if( zBasename!=zName ){
+sqliteFree(zBasename);
+}
+pCol->zName = zName;
+/* Get the typename, type affinity, and collating sequence for the
+** column.
+*/
+memset(&sNC, 0, sizeof(sNC));
+sNC.pSrcList = pSelect->pSrc;
+zType = sqliteStrDup(columnType(&sNC, p, 0, 0, 0));
+pCol->zType = zType;
+pCol->affinity = sqlite3ExprAffinity(p);
+pColl = sqlite3ExprCollSeq(pParse, p);
+if( pColl ){
+pCol->zColl = sqliteStrDup(pColl->zName);
+}
+}
+pTab->iPKey = -1;
+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;
+if( p==0 || p->pSrc==0 || sqlite3MallocFailed() ){
+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("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,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(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(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(&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;
+}
+if( zTName && (zTabName==0 || zTabName[0]==0 ||
+sqlite3StrICmp(zTName, zTabName)!=0) ){
+continue;
+}
+tableSeen = 1;
+for(j=0; j<pTab->nCol; j++){
+Expr *pExpr, *pRight;
+char *zName = pTab->aCol[j].zName;
+if( i>0 ){
+struct SrcList_item *pLeft = &pTabList->a[i-1];
+if( (pLeft->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->pUsing, zName)>=0 ){
+/* In a join with a USING clause, omit columns in the
+** using clause from the table on the right. */
+continue;
+}
+}
+pRight = sqlite3Expr(TK_ID, 0, 0, 0);
+if( pRight==0 ) break;
+setToken(&pRight->token, zName);
+if( zTabName && (longNames || pTabList->nSrc>1) ){
+Expr *pLeft = sqlite3Expr(TK_ID, 0, 0, 0);
+pExpr = sqlite3Expr(TK_DOT, pLeft, pRight, 0);
+if( pExpr==0 ) break;
+setToken(&pLeft->token, zTabName);
+setToken(&pExpr->span, sqlite3MPrintf("%s.%s", zTabName, zName));
+pExpr->span.dyn = 1;
+pExpr->token.z = 0;
+pExpr->token.n = 0;
+pExpr->token.dyn = 0;
+}else{
+pExpr = pRight;
+pExpr->span = pExpr->token;
+}
+if( longNames ){
+pNew = sqlite3ExprListAppend(pNew, pExpr, &pExpr->span);
+}else{
+pNew = sqlite3ExprListAppend(pNew, pExpr, &pRight->token);
+}
+}
+}
+if( !tableSeen ){
+if( zTName ){
+sqlite3ErrorMsg(pParse, "no such table: %s", zTName);
+}else{
+sqlite3ErrorMsg(pParse, "no tables specified");
+}
+rc = 1;
+}
+sqliteFree(zTName);
+}
+}
+sqlite3ExprListDelete(pEList);
+p->pEList = pNew;
+}
+return rc;
+}
+#ifndef SQLITE_OMIT_COMPOUND_SELECT
+/*
+** This routine associates entries in an ORDER BY expression list with
+** columns in a result.  For each ORDER BY expression, the opcode of
+** the top-level node is changed to TK_COLUMN and the iColumn value of
+** the top-level node is filled in with column number and the iTable
+** value of the top-level node is filled with iTable parameter.
+**
+** If there are prior SELECT clauses, they are processed first.  A match
+** in an earlier SELECT takes precedence over a later SELECT.
+**
+** Any entry that does not match is flagged as an error.  The number
+** of errors is returned.
+*/
+static int matchOrderbyToColumn(
+Parse *pParse,          /* A place to leave error messages */
+Select *pSelect,        /* Match to result columns of this SELECT */
+ExprList *pOrderBy,     /* The ORDER BY values to match against columns */
+int iTable,             /* Insert this value in iTable */
+int mustComplete        /* If TRUE all ORDER BYs must match */
+){
+int nErr = 0;
+int i, j;
+ExprList *pEList;
+if( pSelect==0 || pOrderBy==0 ) return 1;
+if( mustComplete ){
+for(i=0; i<pOrderBy->nExpr; i++){ pOrderBy->a[i].done = 0; }
+}
+if( prepSelectStmt(pParse, pSelect) ){
+return 1;
+}
+if( pSelect->pPrior ){
+if( matchOrderbyToColumn(pParse, pSelect->pPrior, pOrderBy, iTable, 0) ){
+return 1;
+}
+}
+pEList = pSelect->pEList;
+for(i=0; i<pOrderBy->nExpr; i++){
+Expr *pE = pOrderBy->a[i].pExpr;
+int iCol = -1;
+if( pOrderBy->a[i].done ) continue;
+if( sqlite3ExprIsInteger(pE, &iCol) ){
+if( iCol<=0 || iCol>pEList->nExpr ){
+sqlite3ErrorMsg(pParse,
+"ORDER BY position %d should be between 1 and %d",
+iCol, pEList->nExpr);
+nErr++;
+break;
+}
+if( !mustComplete ) continue;
+iCol--;
+}
+for(j=0; iCol<0 && j<pEList->nExpr; j++){
+if( pEList->a[j].zName && (pE->op==TK_ID || pE->op==TK_STRING) ){
+char *zName, *zLabel;
+zName = pEList->a[j].zName;
+zLabel = sqlite3NameFromToken(&pE->token);
+assert( zLabel!=0 );
+if( sqlite3StrICmp(zName, zLabel)==0 ){
+iCol = j;
+}
+sqliteFree(zLabel);
+}
+if( iCol<0 && sqlite3ExprCompare(pE, pEList->a[j].pExpr) ){
+iCol = j;
+}
+}
+if( iCol>=0 ){
+pE->op = TK_COLUMN;
+pE->iColumn = iCol;
+pE->iTable = iTable;
+pE->iAgg = -1;
+pOrderBy->a[i].done = 1;
+}
+if( iCol<0 && mustComplete ){
+sqlite3ErrorMsg(pParse,
+"ORDER BY term number %d does not match any result column", i+1);
+nErr++;
+break;
+}
+}
+return nErr;
+}
+#endif /* #ifndef SQLITE_OMIT_COMPOUND_SELECT */
+/*
+** 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);
+}
+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, addr2;
+/*
+** "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;
+pParse->nMem += 2;
+v = sqlite3GetVdbe(pParse);
+if( v==0 ) return;
+sqlite3ExprCode(pParse, p->pLimit);
+sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
+sqlite3VdbeAddOp(v, OP_MemStore, iLimit, 0);
+VdbeComment((v, "# LIMIT counter"));
+sqlite3VdbeAddOp(v, OP_IfMemZero, iLimit, iBreak);
+}
+if( p->pOffset ){
+p->iOffset = iOffset = pParse->nMem++;
+v = sqlite3GetVdbe(pParse);
+if( v==0 ) return;
+sqlite3ExprCode(pParse, p->pOffset);
+sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
+sqlite3VdbeAddOp(v, OP_MemStore, iOffset, p->pLimit==0);
+VdbeComment((v, "# OFFSET counter"));
+addr1 = sqlite3VdbeAddOp(v, OP_IfMemPos, iOffset, 0);
+sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
+sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
+sqlite3VdbeJumpHere(v, addr1);
+if( p->pLimit ){
+sqlite3VdbeAddOp(v, OP_Add, 0, 0);
+}
+}
+if( p->pLimit ){
+addr1 = sqlite3VdbeAddOp(v, OP_IfMemPos, iLimit, 0);
+sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
+sqlite3VdbeAddOp(v, OP_MemInt, -1, iLimit+1);
+addr2 = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
+sqlite3VdbeJumpHere(v, addr1);
+sqlite3VdbeAddOp(v, OP_MemStore, iLimit+1, 1);
+VdbeComment((v, "# LIMIT+OFFSET"));
+sqlite3VdbeJumpHere(v, addr2);
+}
+}
+/*
+** Allocate a virtual index to use for sorting.
+*/
+static void createSortingIndex(Parse *pParse, Select *p, ExprList *pOrderBy){
+if( pOrderBy ){
+int addr;
+assert( pOrderBy->iECursor==0 );
+pOrderBy->iECursor = pParse->nTab++;
+addr = sqlite3VdbeAddOp(pParse->pVdbe, OP_OpenEphemeral,
+pOrderBy->iECursor, pOrderBy->nExpr+1);
+assert( p->addrOpenEphm[2] == -1 );
+p->addrOpenEphm[2] = addr;
+}
+}
+#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 */
+#ifndef SQLITE_OMIT_COMPOUND_SELECT
+/*
+** This routine is called to process a query that is really the union
+** or intersection of two or more separate queries.
+**
+** "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 */
+int eDest,            /* \___  Store query results as specified */
+int iParm,            /* /     by these two parameters.         */
+char *aff             /* If eDest is SRT_Union, the affinity string */
+){
+int rc = SQLITE_OK;   /* Success code from a subroutine */
+Select *pPrior;       /* Another SELECT immediately to our left */
+Vdbe *v;              /* Generate code to this VDBE */
+int nCol;             /* Number of columns in the result set */
+ExprList *pOrderBy;   /* The ORDER BY clause on p */
+int aSetP2[2];        /* Set P2 value of these op to number of columns */
+int nSetP2 = 0;       /* Number of slots in aSetP2[] used */
+/* 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.
+*/
+if( p==0 || p->pPrior==0 ){
+rc = 1;
+goto multi_select_end;
+}
+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;
+}
+/* Make sure we have a valid query engine.  If not, create a new one.
+*/
+v = sqlite3GetVdbe(pParse);
+if( v==0 ){
+rc = 1;
+goto multi_select_end;
+}
+/* Create the destination temporary table if necessary
+*/
+if( eDest==SRT_EphemTab ){
+assert( p->pEList );
+assert( nSetP2<sizeof(aSetP2)/sizeof(aSetP2[0]) );
+aSetP2[nSetP2++] = sqlite3VdbeAddOp(v, OP_OpenEphemeral, iParm, 0);
+eDest = SRT_Table;
+}
+/* Generate code for the left and right SELECT statements.
+*/
+pOrderBy = p->pOrderBy;
+switch( p->op ){
+case TK_ALL: {
+if( pOrderBy==0 ){
+int addr = 0;
+assert( !pPrior->pLimit );
+pPrior->pLimit = p->pLimit;
+pPrior->pOffset = p->pOffset;
+rc = sqlite3Select(pParse, pPrior, eDest, iParm, 0, 0, 0, aff);
+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>=0 ){
+addr = sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, 0);
+VdbeComment((v, "# Jump ahead if LIMIT reached"));
+}
+rc = sqlite3Select(pParse, p, eDest, iParm, 0, 0, 0, aff);
+p->pPrior = pPrior;
+if( rc ){
+goto multi_select_end;
+}
+if( addr ){
+sqlite3VdbeJumpHere(v, addr);
+}
+break;
+}
+/* For UNION ALL ... ORDER BY fall through to the next case */
+}
+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;
+priorOp = p->op==TK_ALL ? SRT_Table : SRT_Union;
+if( eDest==priorOp && pOrderBy==0 && !p->pLimit && !p->pOffset ){
+/* We can reuse a temporary table generated by a SELECT to our
+** right.
+*/
+unionTab = iParm;
+}else{
+/* We will need to create our own temporary table to hold the
+** intermediate results.
+*/
+unionTab = pParse->nTab++;
+if( pOrderBy && matchOrderbyToColumn(pParse, p, pOrderBy, unionTab,1) ){
+rc = 1;
+goto multi_select_end;
+}
+addr = sqlite3VdbeAddOp(v, OP_OpenEphemeral, unionTab, 0);
+if( priorOp==SRT_Table ){
+assert( nSetP2<sizeof(aSetP2)/sizeof(aSetP2[0]) );
+aSetP2[nSetP2++] = addr;
+}else{
+assert( p->addrOpenEphm[0] == -1 );
+p->addrOpenEphm[0] = addr;
+p->pRightmost->usesEphm = 1;
+}
+createSortingIndex(pParse, p, pOrderBy);
+assert( p->pEList );
+}
+/* Code the SELECT statements to our left
+*/
+assert( !pPrior->pOrderBy );
+rc = sqlite3Select(pParse, pPrior, priorOp, unionTab, 0, 0, 0, aff);
+if( rc ){
+goto multi_select_end;
+}
+/* Code the current SELECT statement
+*/
+switch( p->op ){
+case TK_EXCEPT:  op = SRT_Except;   break;
+case TK_UNION:   op = SRT_Union;    break;
+case TK_ALL:     op = SRT_Table;    break;
+}
+p->pPrior = 0;
+p->pOrderBy = 0;
+p->disallowOrderBy = pOrderBy!=0;
+pLimit = p->pLimit;
+p->pLimit = 0;
+pOffset = p->pOffset;
+p->pOffset = 0;
+rc = sqlite3Select(pParse, p, op, unionTab, 0, 0, 0, aff);
+p->pPrior = pPrior;
+p->pOrderBy = pOrderBy;
+sqlite3ExprDelete(p->pLimit);
+p->pLimit = pLimit;
+p->pOffset = pOffset;
+p->iLimit = -1;
+p->iOffset = -1;
+if( rc ){
+goto multi_select_end;
+}
+/* Convert the data in the temporary table into whatever form
+** it is that we currently need.
+*/
+if( eDest!=priorOp || unionTab!=iParm ){
+int iCont, iBreak, iStart;
+assert( p->pEList );
+if( 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);
+sqlite3VdbeAddOp(v, OP_Rewind, unionTab, iBreak);
+iStart = sqlite3VdbeCurrentAddr(v);
+rc = selectInnerLoop(pParse, p, p->pEList, unionTab, p->pEList->nExpr,
+pOrderBy, -1, eDest, iParm,
+iCont, iBreak, 0);
+if( rc ){
+rc = 1;
+goto multi_select_end;
+}
+sqlite3VdbeResolveLabel(v, iCont);
+sqlite3VdbeAddOp(v, OP_Next, unionTab, iStart);
+sqlite3VdbeResolveLabel(v, iBreak);
+sqlite3VdbeAddOp(v, OP_Close, unionTab, 0);
+}
+break;
+}
+case TK_INTERSECT: {
+int tab1, tab2;
+int iCont, iBreak, iStart;
+Expr *pLimit, *pOffset;
+int addr;
+/* 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++;
+if( pOrderBy && matchOrderbyToColumn(pParse,p,pOrderBy,tab1,1) ){
+rc = 1;
+goto multi_select_end;
+}
+createSortingIndex(pParse, p, pOrderBy);
+addr = sqlite3VdbeAddOp(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".
+*/
+rc = sqlite3Select(pParse, pPrior, SRT_Union, tab1, 0, 0, 0, aff);
+if( rc ){
+goto multi_select_end;
+}
+/* Code the current SELECT into temporary table "tab2"
+*/
+addr = sqlite3VdbeAddOp(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;
+rc = sqlite3Select(pParse, p, SRT_Union, tab2, 0, 0, 0, aff);
+p->pPrior = pPrior;
+sqlite3ExprDelete(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( 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);
+sqlite3VdbeAddOp(v, OP_Rewind, tab1, iBreak);
+iStart = sqlite3VdbeAddOp(v, OP_RowKey, tab1, 0);
+sqlite3VdbeAddOp(v, OP_NotFound, tab2, iCont);
+rc = selectInnerLoop(pParse, p, p->pEList, tab1, p->pEList->nExpr,
+pOrderBy, -1, eDest, iParm,
+iCont, iBreak, 0);
+if( rc ){
+rc = 1;
+goto multi_select_end;
+}
+sqlite3VdbeResolveLabel(v, iCont);
+sqlite3VdbeAddOp(v, OP_Next, tab1, iStart);
+sqlite3VdbeResolveLabel(v, iBreak);
+sqlite3VdbeAddOp(v, OP_Close, tab2, 0);
+sqlite3VdbeAddOp(v, OP_Close, tab1, 0);
+break;
+}
+}
+/* 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;
+}
+/* Set the number of columns in temporary tables
+*/
+nCol = p->pEList->nExpr;
+while( nSetP2 ){
+sqlite3VdbeChangeP2(v, aSetP2[--nSetP2], nCol);
+}
+/* Compute collating sequences used by either the ORDER BY clause or
+** by any temporary tables needed to implement the compound select.
+** Attach the KeyInfo structure to all temporary tables.  Invoke the
+** ORDER BY processing if there is an ORDER BY clause.
+**
+** 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( pOrderBy || p->usesEphm ){
+int i;                        /* Loop counter */
+KeyInfo *pKeyInfo;            /* Collating sequence for the result set */
+Select *pLoop;                /* For looping through SELECT statements */
+int nKeyCol;                  /* Number of entries in pKeyInfo->aCol[] */
+CollSeq **apColl;
+CollSeq **aCopy;
+assert( p->pRightmost==p );
+nKeyCol = nCol + (pOrderBy ? pOrderBy->nExpr : 0);
+pKeyInfo = sqliteMalloc(sizeof(*pKeyInfo)+nKeyCol*(sizeof(CollSeq*) + 1));
+if( !pKeyInfo ){
+rc = SQLITE_NOMEM;
+goto multi_select_end;
+}
+pKeyInfo->enc = ENC(pParse->db);
+pKeyInfo->nField = nCol;
+for(i=0, apColl=pKeyInfo->aColl; i<nCol; i++, apColl++){
+*apColl = multiSelectCollSeq(pParse, p, i);
+if( 0==*apColl ){
+*apColl = pParse->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);
+sqlite3VdbeChangeP3(v, addr, (char*)pKeyInfo, P3_KEYINFO);
+}
+}
+if( pOrderBy ){
+struct ExprList_item *pOTerm = pOrderBy->a;
+int nOrderByExpr = pOrderBy->nExpr;
+int addr;
+u8 *pSortOrder;
+aCopy = &pKeyInfo->aColl[nOrderByExpr];
+pSortOrder = pKeyInfo->aSortOrder = (u8*)&aCopy[nCol];
+memcpy(aCopy, pKeyInfo->aColl, nCol*sizeof(CollSeq*));
+apColl = pKeyInfo->aColl;
+for(i=0; i<nOrderByExpr; i++, pOTerm++, apColl++, pSortOrder++){
+Expr *pExpr = pOTerm->pExpr;
+char *zName = pOTerm->zName;
+assert( pExpr->op==TK_COLUMN && pExpr->iColumn<nCol );
+if( zName ){
+*apColl = sqlite3LocateCollSeq(pParse, zName, -1);
+}else{
+*apColl = aCopy[pExpr->iColumn];
+}
+*pSortOrder = pOTerm->sortOrder;
+}
+assert( p->pRightmost==p );
+assert( p->addrOpenEphm[2]>=0 );
+addr = p->addrOpenEphm[2];
+sqlite3VdbeChangeP2(v, addr, p->pEList->nExpr+2);
+pKeyInfo->nField = nOrderByExpr;
+sqlite3VdbeChangeP3(v, addr, (char*)pKeyInfo, P3_KEYINFO_HANDOFF);
+pKeyInfo = 0;
+generateSortTail(pParse, p, v, p->pEList->nExpr, eDest, iParm);
+}
+sqliteFree(pKeyInfo);
+}
+multi_select_end:
+return rc;
+}
+#endif /* SQLITE_OMIT_COMPOUND_SELECT */
+#ifndef SQLITE_OMIT_VIEW
+/*
+** 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 substExprList(ExprList*,int,ExprList*);  /* Forward Decl */
+static void substSelect(Select *, int, ExprList *);  /* Forward Decl */
+static void substExpr(Expr *pExpr, int iTable, ExprList *pEList){
+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(pNew->pLeft);
+assert( pExpr->pRight==0 );
+pExpr->pRight = sqlite3ExprDup(pNew->pRight);
+assert( pExpr->pList==0 );
+pExpr->pList = sqlite3ExprListDup(pNew->pList);
+pExpr->iTable = pNew->iTable;
+pExpr->pTab = pNew->pTab;
+pExpr->iColumn = pNew->iColumn;
+pExpr->iAgg = pNew->iAgg;
+sqlite3TokenCopy(&pExpr->token, &pNew->token);
+sqlite3TokenCopy(&pExpr->span, &pNew->span);
+pExpr->pSelect = sqlite3SelectDup(pNew->pSelect);
+pExpr->flags = pNew->flags;
+}
+}else{
+substExpr(pExpr->pLeft, iTable, pEList);
+substExpr(pExpr->pRight, iTable, pEList);
+substSelect(pExpr->pSelect, iTable, pEList);
+substExprList(pExpr->pList, iTable, pEList);
+}
+}
+static void substExprList(ExprList *pList, int iTable, ExprList *pEList){
+int i;
+if( pList==0 ) return;
+for(i=0; i<pList->nExpr; i++){
+substExpr(pList->a[i].pExpr, iTable, pEList);
+}
+}
+static void substSelect(Select *p, int iTable, ExprList *pEList){
+if( !p ) return;
+substExprList(p->pEList, iTable, pEList);
+substExprList(p->pGroupBy, iTable, pEList);
+substExprList(p->pOrderBy, iTable, pEList);
+substExpr(p->pHaving, iTable, pEList);
+substExpr(p->pWhere, iTable, pEList);
+}
+#endif /* !defined(SQLITE_OMIT_VIEW) */
+#ifndef 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
+**
+** 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(
+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 */
+){
+Select *pSub;       /* The inner query or "subquery" */
+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 */
+/* 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];
+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( 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) */
+}
+/* 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 && iFrom>0 && (pSrc->a[iFrom-1].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( iFrom>0 && (pSrc->a[iFrom-1].jointype & JT_OUTER)!=0
+&& pSub->pWhere!=0 ){
+return 0;
+}
+/* If we reach this point, it means flattening is permitted for the
+** iFrom-th entry of the FROM clause in the outer query.
+*/
+/* 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.
+*/
+iParent = pSubitem->iCursor;
+{
+int nSubSrc = pSubSrc->nSrc;
+int jointype = pSubitem->jointype;
+sqlite3DeleteTable(0, pSubitem->pTab);
+sqliteFree(pSubitem->zDatabase);
+sqliteFree(pSubitem->zName);
+sqliteFree(pSubitem->zAlias);
+if( nSubSrc>1 ){
+int extra = nSubSrc - 1;
+for(i=1; i<nSubSrc; i++){
+pSrc = sqlite3SrcListAppend(pSrc, 0, 0);
+}
+p->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+nSubSrc-1].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 = p->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 = sqliteStrNDup((char*)pExpr->span.z, pExpr->span.n);
+}
+}
+substExprList(p->pEList, iParent, pSub->pEList);
+if( isAgg ){
+substExprList(p->pGroupBy, iParent, pSub->pEList);
+substExpr(p->pHaving, iParent, pSub->pEList);
+}
+if( pSub->pOrderBy ){
+assert( p->pOrderBy==0 );
+p->pOrderBy = pSub->pOrderBy;
+pSub->pOrderBy = 0;
+}else if( p->pOrderBy ){
+substExprList(p->pOrderBy, iParent, pSub->pEList);
+}
+if( pSub->pWhere ){
+pWhere = sqlite3ExprDup(pSub->pWhere);
+}else{
+pWhere = 0;
+}
+if( subqueryIsAgg ){
+assert( p->pHaving==0 );
+p->pHaving = p->pWhere;
+p->pWhere = pWhere;
+substExpr(p->pHaving, iParent, pSub->pEList);
+p->pHaving = sqlite3ExprAnd(p->pHaving, sqlite3ExprDup(pSub->pHaving));
+assert( p->pGroupBy==0 );
+p->pGroupBy = sqlite3ExprListDup(pSub->pGroupBy);
+}else{
+substExpr(p->pWhere, iParent, pSub->pEList);
+p->pWhere = sqlite3ExprAnd(p->pWhere, pWhere);
+}
+/* The flattened query is distinct if either the inner or the
+** outer query is distinct.
+*/
+p->isDistinct = p->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 ){
+p->pLimit = pSub->pLimit;
+pSub->pLimit = 0;
+}
+/* Finially, delete what is left of the subquery and return
+** success.
+*/
+sqlite3SelectDelete(pSub);
+return 1;
+}
+#endif /* SQLITE_OMIT_VIEW */
+/*
+** Analyze the SELECT statement passed in as an argument to see if it
+** is a simple min() or max() query.  If it is and this query can be
+** satisfied using a single seek to the beginning or end of an index,
+** then generate the code for this SELECT and return 1.  If this is not a
+** simple min() or max() query, then return 0;
+**
+** A simply min() or max() query looks like this:
+**
+**    SELECT min(a) FROM table;
+**    SELECT max(a) FROM table;
+**
+** The query may have only a single table in its FROM argument.  There
+** can be no GROUP BY or HAVING or WHERE clauses.  The result set must
+** be the min() or max() of a single column of the table.  The column
+** in the min() or max() function must be indexed.
+**
+** The parameters to this routine are the same as for sqlite3Select().
+** See the header comment on that routine for additional information.
+*/
+static int simpleMinMaxQuery(Parse *pParse, Select *p, int eDest, int iParm){
+Expr *pExpr;
+int iCol;
+Table *pTab;
+Index *pIdx;
+int base;
+Vdbe *v;
+int seekOp;
+ExprList *pEList, *pList, eList;
+struct ExprList_item eListItem;
+SrcList *pSrc;
+int brk;
+int iDb;
+/* Check to see if this query is a simple min() or max() query.  Return
+** zero if it is  not.
+*/
+if( p->pGroupBy || p->pHaving || p->pWhere ) return 0;
+pSrc = p->pSrc;
+if( pSrc->nSrc!=1 ) return 0;
+pEList = p->pEList;
+if( pEList->nExpr!=1 ) return 0;
+pExpr = pEList->a[0].pExpr;
+if( pExpr->op!=TK_AGG_FUNCTION ) return 0;
+pList = pExpr->pList;
+if( pList==0 || pList->nExpr!=1 ) return 0;
+if( pExpr->token.n!=3 ) return 0;
+if( sqlite3StrNICmp((char*)pExpr->token.z,"min",3)==0 ){
+seekOp = OP_Rewind;
+}else if( sqlite3StrNICmp((char*)pExpr->token.z,"max",3)==0 ){
+seekOp = OP_Last;
+}else{
+return 0;
+}
+pExpr = pList->a[0].pExpr;
+if( pExpr->op!=TK_COLUMN ) return 0;
+iCol = pExpr->iColumn;
+pTab = pSrc->a[0].pTab;
+/* If we get to here, it means the query is of the correct form.
+** Check to make sure we have an index and make pIdx point to the
+** appropriate index.  If the min() or max() is on an INTEGER PRIMARY
+** key column, no index is necessary so set pIdx to NULL.  If no
+** usable index is found, return 0.
+*/
+if( iCol<0 ){
+pIdx = 0;
+}else{
+CollSeq *pColl = sqlite3ExprCollSeq(pParse, pExpr);
+if( pColl==0 ) return 0;
+for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+assert( pIdx->nColumn>=1 );
+if( pIdx->aiColumn[0]==iCol &&
+0==sqlite3StrICmp(pIdx->azColl[0], pColl->zName) ){
+break;
+}
+}
+if( pIdx==0 ) return 0;
+}
+/* Identify column types if we will be using the callback.  This
+** step is skipped if the output is going to a table or a memory cell.
+** The column names have already been generated in the calling function.
+*/
+v = sqlite3GetVdbe(pParse);
+if( v==0 ) return 0;
+/* If the output is destined for a temporary table, open that table.
+*/
+if( eDest==SRT_EphemTab ){
+sqlite3VdbeAddOp(v, OP_OpenEphemeral, iParm, 1);
+}
+/* Generating code to find the min or the max.  Basically all we have
+** to do is find the first or the last entry in the chosen index.  If
+** the min() or max() is on the INTEGER PRIMARY KEY, then find the first
+** or last entry in the main table.
+*/
+iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
+assert( iDb>=0 || pTab->isEphem );
+sqlite3CodeVerifySchema(pParse, iDb);
+sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
+base = pSrc->a[0].iCursor;
+brk = sqlite3VdbeMakeLabel(v);
+computeLimitRegisters(pParse, p, brk);
+if( pSrc->a[0].pSelect==0 ){
+sqlite3OpenTable(pParse, base, iDb, pTab, OP_OpenRead);
+}
+if( pIdx==0 ){
+sqlite3VdbeAddOp(v, seekOp, base, 0);
+}else{
+/* Even though the cursor used to open the index here is closed
+** as soon as a single value has been read from it, allocate it
+** using (pParse->nTab++) to prevent the cursor id from being
+** reused. This is important for statements of the form
+** "INSERT INTO x SELECT max() FROM x".
+*/
+int iIdx;
+KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
+iIdx = pParse->nTab++;
+assert( pIdx->pSchema==pTab->pSchema );
+sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
+sqlite3VdbeOp3(v, OP_OpenRead, iIdx, pIdx->tnum,
+(char*)pKey, P3_KEYINFO_HANDOFF);
+if( seekOp==OP_Rewind ){
+sqlite3VdbeAddOp(v, OP_Null, 0, 0);
+sqlite3VdbeAddOp(v, OP_MakeRecord, 1, 0);
+seekOp = OP_MoveGt;
+}
+sqlite3VdbeAddOp(v, seekOp, iIdx, 0);
+sqlite3VdbeAddOp(v, OP_IdxRowid, iIdx, 0);
+sqlite3VdbeAddOp(v, OP_Close, iIdx, 0);
+sqlite3VdbeAddOp(v, OP_MoveGe, base, 0);
+}
+eList.nExpr = 1;
+memset(&eListItem, 0, sizeof(eListItem));
+eList.a = &eListItem;
+eList.a[0].pExpr = pExpr;
+selectInnerLoop(pParse, p, &eList, 0, 0, 0, -1, eDest, iParm, brk, brk, 0);
+sqlite3VdbeResolveLabel(v, brk);
+sqlite3VdbeAddOp(v, OP_Close, base, 0);
+return 1;
+}
+/*
+** Analyze and ORDER BY or GROUP BY clause in a SELECT statement.  Return
+** the number of errors seen.
+**
+** An ORDER BY or GROUP BY is a list of expressions.  If any expression
+** is an integer constant, then that expression is replaced by the
+** corresponding entry in the result set.
+*/
+static int processOrderGroupBy(
+NameContext *pNC,     /* Name context of the SELECT statement. */
+ExprList *pOrderBy,   /* The ORDER BY or GROUP BY clause to be processed */
+const char *zType     /* Either "ORDER" or "GROUP", as appropriate */
+){
+int i;
+ExprList *pEList = pNC->pEList;     /* The result set of the SELECT */
+Parse *pParse = pNC->pParse;     /* The result set of the SELECT */
+assert( pEList );
+if( pOrderBy==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 ){
+sqlite3ExprDelete(pE);
+pE = pOrderBy->a[i].pExpr = sqlite3ExprDup(pEList->a[iCol-1].pExpr);
+}else{
+sqlite3ErrorMsg(pParse,
+"%s BY column number %d out of range - should be "
+"between 1 and %d", zType, iCol, pEList->nExpr);
+return 1;
+}
+}
+if( sqlite3ExprResolveNames(pNC, pE) ){
+return 1;
+}
+}
+return 0;
+}
+/*
+** 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) ||
+processOrderGroupBy(&sNC, p->pOrderBy, "ORDER") ||
+processOrderGroupBy(&sNC, pGroupBy, "GROUP")
+){
+return SQLITE_ERROR;
+}
+/* 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;
+}
+}
+}
+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++){
+sqlite3VdbeAddOp(v, OP_MemNull, pAggInfo->aCol[i].iMem, 0);
+}
+for(pFunc=pAggInfo->aFunc, i=0; i<pAggInfo->nFunc; i++, pFunc++){
+sqlite3VdbeAddOp(v, OP_MemNull, pFunc->iMem, 0);
+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);
+sqlite3VdbeOp3(v, OP_OpenEphemeral, pFunc->iDistinct, 0,
+(char*)pKeyInfo, P3_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;
+sqlite3VdbeOp3(v, OP_AggFinal, pF->iMem, pList ? pList->nExpr : 0,
+(void*)pF->pFunc, P3_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;
+ExprList *pList = pF->pExpr->pList;
+if( pList ){
+nArg = pList->nExpr;
+sqlite3ExprCodeExprList(pParse, pList);
+}else{
+nArg = 0;
+}
+if( pF->iDistinct>=0 ){
+addrNext = sqlite3VdbeMakeLabel(v);
+assert( nArg==1 );
+codeDistinct(v, pF->iDistinct, addrNext, 1);
+}
+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;
+}
+sqlite3VdbeOp3(v, OP_CollSeq, 0, 0, (char *)pColl, P3_COLLSEQ);
+}
+sqlite3VdbeOp3(v, OP_AggStep, pF->iMem, nArg, (void*)pF->pFunc, P3_FUNCDEF);
+if( addrNext ){
+sqlite3VdbeResolveLabel(v, addrNext);
+}
+}
+for(i=0, pC=pAggInfo->aCol; i<pAggInfo->nAccumulator; i++, pC++){
+sqlite3ExprCode(pParse, pC->pExpr);
+sqlite3VdbeAddOp(v, OP_MemStore, pC->iMem, 1);
+}
+pAggInfo->directMode = 0;
+}
+/*
+** Generate code for the given SELECT statement.
+**
+** The results are distributed in various ways depending on the
+** value of eDest and iParm.
+**
+**     eDest Value       Result
+**     ------------    -------------------------------------------
+**     SRT_Callback    Invoke the callback for each row of the result.
+**
+**     SRT_Mem         Store first result in memory cell iParm
+**
+**     SRT_Set         Store results as keys of table iParm.
+**
+**     SRT_Union       Store results as a key in a temporary table iParm
+**
+**     SRT_Except      Remove results from the temporary table iParm.
+**
+**     SRT_Table       Store results in temporary table iParm
+**
+** The table above is incomplete.  Additional eDist value have be added
+** since this comment was written.  See the selectInnerLoop() function for
+** a complete 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. */
+int eDest,             /* How to dispose of the results */
+int iParm,             /* A parameter used by the eDest disposal method */
+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 */
+char *aff              /* If eDest is SRT_Union, the affinity string */
+){
+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 */
+if( p==0 || sqlite3MallocFailed() || pParse->nErr ){
+return 1;
+}
+if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;
+memset(&sAggInfo, 0, sizeof(sAggInfo));
+#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;
+for(pLoop=p; pLoop; pLoop=pLoop->pPrior){
+pLoop->pRightmost = p;
+}
+}
+return multiSelect(pParse, p, eDest, iParm, aff);
+}
+#endif
+pOrderBy = p->pOrderBy;
+if( IgnorableOrderby(eDest) ){
+p->pOrderBy = 0;
+}
+if( sqlite3SelectResolve(pParse, p, 0) ){
+goto select_end;
+}
+p->pOrderBy = pOrderBy;
+/* Make local copies of the parameters for this query.
+*/
+pTabList = p->pSrc;
+pWhere = p->pWhere;
+pGroupBy = p->pGroupBy;
+pHaving = p->pHaving;
+isAgg = p->isAgg;
+isDistinct = p->isDistinct;
+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;
+/* If writing to memory or generating a set
+** only a single column may be output.
+*/
+#ifndef SQLITE_OMIT_SUBQUERY
+if( (eDest==SRT_Mem || eDest==SRT_Set) && pEList->nExpr>1 ){
+sqlite3ErrorMsg(pParse, "only a single result allowed for "
+"a SELECT that is part of an expression");
+goto select_end;
+}
+#endif
+/* ORDER BY is ignored for some destinations.
+*/
+if( IgnorableOrderby(eDest) ){
+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; i<pTabList->nSrc; i++){
+const char *zSavedAuthContext = 0;
+int needRestoreContext;
+struct SrcList_item *pItem = &pTabList->a[i];
+if( pItem->pSelect==0 || pItem->isPopulated ) continue;
+if( pItem->zName!=0 ){
+zSavedAuthContext = pParse->zAuthContext;
+pParse->zAuthContext = pItem->zName;
+needRestoreContext = 1;
+}else{
+needRestoreContext = 0;
+}
+sqlite3Select(pParse, pItem->pSelect, SRT_EphemTab,
+pItem->iCursor, p, i, &isAgg, 0);
+if( needRestoreContext ){
+pParse->zAuthContext = zSavedAuthContext;
+}
+pTabList = p->pSrc;
+pWhere = p->pWhere;
+if( !IgnorableOrderby(eDest) ){
+pOrderBy = p->pOrderBy;
+}
+pGroupBy = p->pGroupBy;
+pHaving = p->pHaving;
+isDistinct = p->isDistinct;
+}
+#endif
+/* Check for the special case of a min() or max() function by itself
+** in the result set.
+*/
+if( simpleMinMaxQuery(pParse, p, eDest, iParm) ){
+rc = 0;
+goto select_end;
+}
+/* Check to see if this is a subquery that can be "flattened" into its parent.
+** If flattening is a possiblity, do so and return immediately.
+*/
+#ifndef SQLITE_OMIT_VIEW
+if( pParent && pParentAgg &&
+flattenSubquery(pParent, parentTab, *pParentAgg, isAgg) ){
+if( isAgg ) *pParentAgg = 1;
+goto select_end;
+}
+#endif
+/* If there is an ORDER BY clause, resolve any collation sequences
+** names that have been explicitly specified and create a sorting index.
+**
+** 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 ){
+struct ExprList_item *pTerm;
+KeyInfo *pKeyInfo;
+for(i=0, pTerm=pOrderBy->a; i<pOrderBy->nExpr; i++, pTerm++){
+if( pTerm->zName ){
+pTerm->pExpr->pColl = sqlite3LocateCollSeq(pParse, pTerm->zName, -1);
+}
+}
+if( pParse->nErr ){
+goto select_end;
+}
+pKeyInfo = keyInfoFromExprList(pParse, pOrderBy);
+pOrderBy->iECursor = pParse->nTab++;
+p->addrOpenEphm[2] = addrSortIndex =
+sqlite3VdbeOp3(v, OP_OpenEphemeral, pOrderBy->iECursor, pOrderBy->nExpr+2,                     (char*)pKeyInfo, P3_KEYINFO_HANDOFF);
+}else{
+addrSortIndex = -1;
+}
+/* If the output is destined for a temporary table, open that table.
+*/
+if( eDest==SRT_EphemTab ){
+sqlite3VdbeAddOp(v, OP_OpenEphemeral, 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;
+distinct = pParse->nTab++;
+pKeyInfo = keyInfoFromExprList(pParse, p->pEList);
+sqlite3VdbeOp3(v, OP_OpenEphemeral, distinct, 0,
+(char*)pKeyInfo, P3_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);
+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
+*/
+if( selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, eDest,
+iParm, pWInfo->iContinue, pWInfo->iBreak, aff) ){
+goto select_end;
+}
+/* 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 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 addrGroupByChange;  /* Code that runs when any GROUP BY term changes */
+int addrProcessRow;     /* Code to process a single input row */
+int addrEnd;            /* End of all processing */
+int addrSortingIdx;     /* The OP_OpenEphemeral for the sorting index */
+int addrReset;          /* Subroutine for resetting the accumulator */
+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;
+if( sqlite3ExprAnalyzeAggList(&sNC, pEList) ){
+goto select_end;
+}
+if( sqlite3ExprAnalyzeAggList(&sNC, pOrderBy) ){
+goto select_end;
+}
+if( pHaving && sqlite3ExprAnalyzeAggregates(&sNC, pHaving) ){
+goto select_end;
+}
+sAggInfo.nAccumulator = sAggInfo.nColumn;
+for(i=0; i<sAggInfo.nFunc; i++){
+if( sqlite3ExprAnalyzeAggList(&sNC, sAggInfo.aFunc[i].pExpr->pList) ){
+goto select_end;
+}
+}
+if( sqlite3MallocFailed() ) goto select_end;
+/* Processing for aggregates with GROUP BY is very different and
+** much more complex tha aggregates without a GROUP BY.
+*/
+if( pGroupBy ){
+KeyInfo *pKeyInfo;  /* Keying information for the group by clause */
+/* Create labels that we will be needing
+*/
+addrInitializeLoop = sqlite3VdbeMakeLabel(v);
+addrGroupByChange = sqlite3VdbeMakeLabel(v);
+addrProcessRow = 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 =
+sqlite3VdbeOp3(v, OP_OpenEphemeral, sAggInfo.sortingIdx,
+sAggInfo.nSortingColumn,
+(char*)pKeyInfo, P3_KEYINFO_HANDOFF);
+/* Initialize memory locations used by GROUP BY aggregate processing
+*/
+iUseFlag = pParse->nMem++;
+iAbortFlag = pParse->nMem++;
+iAMem = pParse->nMem;
+pParse->nMem += pGroupBy->nExpr;
+iBMem = pParse->nMem;
+pParse->nMem += pGroupBy->nExpr;
+sqlite3VdbeAddOp(v, OP_MemInt, 0, iAbortFlag);
+VdbeComment((v, "# clear abort flag"));
+sqlite3VdbeAddOp(v, OP_MemInt, 0, iUseFlag);
+VdbeComment((v, "# indicate accumulator empty"));
+sqlite3VdbeAddOp(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);
+sqlite3VdbeAddOp(v, OP_MemInt, 1, iAbortFlag);
+VdbeComment((v, "# set abort flag"));
+sqlite3VdbeAddOp(v, OP_Return, 0, 0);
+addrOutputRow = sqlite3VdbeCurrentAddr(v);
+sqlite3VdbeAddOp(v, OP_IfMemPos, iUseFlag, addrOutputRow+2);
+VdbeComment((v, "# Groupby result generator entry point"));
+sqlite3VdbeAddOp(v, OP_Return, 0, 0);
+finalizeAggFunctions(pParse, &sAggInfo);
+if( pHaving ){
+sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, 1);
+}
+rc = selectInnerLoop(pParse, p, p->pEList, 0, 0, pOrderBy,
+distinct, eDest, iParm,
+addrOutputRow+1, addrSetAbort, aff);
+if( rc ){
+goto select_end;
+}
+sqlite3VdbeAddOp(v, OP_Return, 0, 0);
+VdbeComment((v, "# end groupby result generator"));
+/* Generate a subroutine that will reset the group-by accumulator
+*/
+addrReset = sqlite3VdbeCurrentAddr(v);
+resetAccumulator(pParse, &sAggInfo);
+sqlite3VdbeAddOp(v, OP_Return, 0, 0);
+/* 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);
+sqlite3VdbeAddOp(v, OP_Gosub, 0, addrReset);
+pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pGroupBy);
+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
+*/
+groupBySort = 1;
+sqlite3ExprCodeExprList(pParse, pGroupBy);
+sqlite3VdbeAddOp(v, OP_Sequence, sAggInfo.sortingIdx, 0);
+j = pGroupBy->nExpr+1;
+for(i=0; i<sAggInfo.nColumn; i++){
+struct AggInfo_col *pCol = &sAggInfo.aCol[i];
+if( pCol->iSorterColumn<j ) continue;
+if( pCol->iColumn<0 ){
+sqlite3VdbeAddOp(v, OP_Rowid, pCol->iTable, 0);
+}else{
+sqlite3VdbeAddOp(v, OP_Column, pCol->iTable, pCol->iColumn);
+}
+j++;
+}
+sqlite3VdbeAddOp(v, OP_MakeRecord, j, 0);
+sqlite3VdbeAddOp(v, OP_IdxInsert, sAggInfo.sortingIdx, 0);
+sqlite3WhereEnd(pWInfo);
+sqlite3VdbeAddOp(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 ){
+sqlite3VdbeAddOp(v, OP_Column, sAggInfo.sortingIdx, j);
+}else{
+sAggInfo.directMode = 1;
+sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr);
+}
+sqlite3VdbeAddOp(v, OP_MemStore, iBMem+j, j<pGroupBy->nExpr-1);
+}
+for(j=pGroupBy->nExpr-1; j>=0; j--){
+if( j<pGroupBy->nExpr-1 ){
+sqlite3VdbeAddOp(v, OP_MemLoad, iBMem+j, 0);
+}
+sqlite3VdbeAddOp(v, OP_MemLoad, iAMem+j, 0);
+if( j==0 ){
+sqlite3VdbeAddOp(v, OP_Eq, 0x200, addrProcessRow);
+}else{
+sqlite3VdbeAddOp(v, OP_Ne, 0x200, addrGroupByChange);
+}
+sqlite3VdbeChangeP3(v, -1, (void*)pKeyInfo->aColl[j], P3_COLLSEQ);
+}
+/* Generate code that runs whenever the GROUP BY changes.
+** Change 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.
+*/
+sqlite3VdbeResolveLabel(v, addrGroupByChange);
+for(j=0; j<pGroupBy->nExpr; j++){
+sqlite3VdbeAddOp(v, OP_MemMove, iAMem+j, iBMem+j);
+}
+sqlite3VdbeAddOp(v, OP_Gosub, 0, addrOutputRow);
+VdbeComment((v, "# output one row"));
+sqlite3VdbeAddOp(v, OP_IfMemPos, iAbortFlag, addrEnd);
+VdbeComment((v, "# check abort flag"));
+sqlite3VdbeAddOp(v, OP_Gosub, 0, addrReset);
+VdbeComment((v, "# reset accumulator"));
+/* Update the aggregate accumulators based on the content of
+** the current row
+*/
+sqlite3VdbeResolveLabel(v, addrProcessRow);
+updateAccumulator(pParse, &sAggInfo);
+sqlite3VdbeAddOp(v, OP_MemInt, 1, iUseFlag);
+VdbeComment((v, "# indicate data in accumulator"));
+/* End of the loop
+*/
+if( groupBySort ){
+sqlite3VdbeAddOp(v, OP_Next, sAggInfo.sortingIdx, addrTopOfLoop);
+}else{
+sqlite3WhereEnd(pWInfo);
+sqlite3VdbeChangeToNoop(v, addrSortingIdx, 1);
+}
+/* Output the final row of result
+*/
+sqlite3VdbeAddOp(v, OP_Gosub, 0, addrOutputRow);
+VdbeComment((v, "# output final row"));
+} /* endif pGroupBy */
+else {
+/* 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, 0);
+if( pWInfo==0 ) goto select_end;
+updateAccumulator(pParse, &sAggInfo);
+sqlite3WhereEnd(pWInfo);
+finalizeAggFunctions(pParse, &sAggInfo);
+pOrderBy = 0;
+if( pHaving ){
+sqlite3ExprIfFalse(pParse, pHaving, addrEnd, 1);
+}
+selectInnerLoop(pParse, p, p->pEList, 0, 0, 0, -1,
+eDest, iParm, addrEnd, addrEnd, aff);
+}
+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, eDest, iParm);
+}
+#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 && eDest==SRT_Callback ){
+generateColumnNames(pParse, pTabList, pEList);
+}
+sqliteFree(sAggInfo.aCol);
+sqliteFree(sAggInfo.aFunc);
+return rc;
+}