--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/persistentstorage/sql/SQLite364/resolve.c Fri Jan 22 11:06:30 2010 +0200
@@ -0,0 +1,1168 @@
+/*
+** 2008 August 18
+**
+** 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 routines used for walking the parser tree and
+** resolve all identifiers by associating them with a particular
+** table and column.
+**
+** $Id: resolve.c,v 1.9 2008/10/11 16:47:36 drh Exp $
+*/
+#include "sqliteInt.h"
+#include <stdlib.h>
+#include <string.h>
+
+/*
+** Turn the pExpr expression into an alias for the iCol-th column of the
+** result set in pEList.
+**
+** If the result set column is a simple column reference, then this routine
+** makes an exact copy. But for any other kind of expression, this
+** routine make a copy of the result set column as the argument to the
+** TK_AS operator. The TK_AS operator causes the expression to be
+** evaluated just once and then reused for each alias.
+**
+** The reason for suppressing the TK_AS term when the expression is a simple
+** column reference is so that the column reference will be recognized as
+** usable by indices within the WHERE clause processing logic.
+**
+** Hack: The TK_AS operator is inhibited if zType[0]=='G'. This means
+** that in a GROUP BY clause, the expression is evaluated twice. Hence:
+**
+** SELECT random()%5 AS x, count(*) FROM tab GROUP BY x
+**
+** Is equivalent to:
+**
+** SELECT random()%5 AS x, count(*) FROM tab GROUP BY random()%5
+**
+** The result of random()%5 in the GROUP BY clause is probably different
+** from the result in the result-set. We might fix this someday. Or
+** then again, we might not...
+*/
+static void resolveAlias(
+ Parse *pParse, /* Parsing context */
+ ExprList *pEList, /* A result set */
+ int iCol, /* A column in the result set. 0..pEList->nExpr-1 */
+ Expr *pExpr, /* Transform this into an alias to the result set */
+ const char *zType /* "GROUP" or "ORDER" or "" */
+){
+ Expr *pOrig; /* The iCol-th column of the result set */
+ Expr *pDup; /* Copy of pOrig */
+ sqlite3 *db; /* The database connection */
+
+ assert( iCol>=0 && iCol<pEList->nExpr );
+ pOrig = pEList->a[iCol].pExpr;
+ assert( pOrig!=0 );
+ assert( pOrig->flags & EP_Resolved );
+ db = pParse->db;
+ pDup = sqlite3ExprDup(db, pOrig);
+ if( pDup==0 ) return;
+ if( pDup->op!=TK_COLUMN && zType[0]!='G' ){
+ pDup = sqlite3PExpr(pParse, TK_AS, pDup, 0, 0);
+ if( pDup==0 ) return;
+ if( pEList->a[iCol].iAlias==0 ){
+ pEList->a[iCol].iAlias = ++pParse->nAlias;
+ }
+ pDup->iTable = pEList->a[iCol].iAlias;
+ }
+ if( pExpr->flags & EP_ExpCollate ){
+ pDup->pColl = pExpr->pColl;
+ pDup->flags |= EP_ExpCollate;
+ }
+ sqlite3ExprClear(db, pExpr);
+ memcpy(pExpr, pDup, sizeof(*pExpr));
+ sqlite3DbFree(db, pDup);
+}
+
+/*
+** Given the name of a column of the form X.Y.Z or Y.Z or just Z, look up
+** that name in the set of source tables in pSrcList and make the pExpr
+** expression node refer back to that source column. The following changes
+** are made to pExpr:
+**
+** pExpr->iDb Set the index in db->aDb[] of the database X
+** (even if X is implied).
+** pExpr->iTable Set to the cursor number for the table obtained
+** from pSrcList.
+** pExpr->pTab Points to the Table structure of X.Y (even if
+** X and/or Y are implied.)
+** pExpr->iColumn Set to the column number within the table.
+** pExpr->op Set to TK_COLUMN.
+** pExpr->pLeft Any expression this points to is deleted
+** pExpr->pRight Any expression this points to is deleted.
+**
+** The pDbToken is the name of the database (the "X"). This value may be
+** NULL meaning that name is of the form Y.Z or Z. Any available database
+** can be used. The pTableToken is the name of the table (the "Y"). This
+** value can be NULL if pDbToken is also NULL. If pTableToken is NULL it
+** means that the form of the name is Z and that columns from any table
+** can be used.
+**
+** If the name cannot be resolved unambiguously, leave an error message
+** in pParse and return non-zero. Return zero on success.
+*/
+static int lookupName(
+ Parse *pParse, /* The parsing context */
+ Token *pDbToken, /* Name of the database containing table, or NULL */
+ Token *pTableToken, /* Name of table containing column, or NULL */
+ Token *pColumnToken, /* Name of the column. */
+ NameContext *pNC, /* The name context used to resolve the name */
+ Expr *pExpr /* Make this EXPR node point to the selected column */
+){
+ char *zDb = 0; /* Name of the database. The "X" in X.Y.Z */
+ char *zTab = 0; /* Name of the table. The "Y" in X.Y.Z or Y.Z */
+ char *zCol = 0; /* Name of the column. The "Z" */
+ int i, j; /* Loop counters */
+ int cnt = 0; /* Number of matching column names */
+ int cntTab = 0; /* Number of matching table names */
+ sqlite3 *db = pParse->db; /* The database connection */
+ struct SrcList_item *pItem; /* Use for looping over pSrcList items */
+ struct SrcList_item *pMatch = 0; /* The matching pSrcList item */
+ NameContext *pTopNC = pNC; /* First namecontext in the list */
+ Schema *pSchema = 0; /* Schema of the expression */
+
+ assert( pColumnToken && pColumnToken->z ); /* The Z in X.Y.Z cannot be NULL */
+
+ /* Dequote and zero-terminate the names */
+ zDb = sqlite3NameFromToken(db, pDbToken);
+ zTab = sqlite3NameFromToken(db, pTableToken);
+ zCol = sqlite3NameFromToken(db, pColumnToken);
+ if( db->mallocFailed ){
+ goto lookupname_end;
+ }
+
+ /* Initialize the node to no-match */
+ pExpr->iTable = -1;
+ pExpr->pTab = 0;
+
+ /* Start at the inner-most context and move outward until a match is found */
+ while( pNC && cnt==0 ){
+ ExprList *pEList;
+ SrcList *pSrcList = pNC->pSrcList;
+
+ if( pSrcList ){
+ for(i=0, pItem=pSrcList->a; i<pSrcList->nSrc; i++, pItem++){
+ Table *pTab;
+ int iDb;
+ Column *pCol;
+
+ pTab = pItem->pTab;
+ assert( pTab!=0 && pTab->zName!=0 );
+ iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+ assert( pTab->nCol>0 );
+ if( zTab ){
+ if( pItem->zAlias ){
+ char *zTabName = pItem->zAlias;
+ if( sqlite3StrICmp(zTabName, zTab)!=0 ) continue;
+ }else{
+ char *zTabName = pTab->zName;
+ if( zTabName==0 || sqlite3StrICmp(zTabName, zTab)!=0 ) continue;
+ if( zDb!=0 && sqlite3StrICmp(db->aDb[iDb].zName, zDb)!=0 ){
+ continue;
+ }
+ }
+ }
+ if( 0==(cntTab++) ){
+ pExpr->iTable = pItem->iCursor;
+ pExpr->pTab = pTab;
+ pSchema = pTab->pSchema;
+ pMatch = pItem;
+ }
+ for(j=0, pCol=pTab->aCol; j<pTab->nCol; j++, pCol++){
+ if( sqlite3StrICmp(pCol->zName, zCol)==0 ){
+ IdList *pUsing;
+ cnt++;
+ pExpr->iTable = pItem->iCursor;
+ pExpr->pTab = pTab;
+ pMatch = pItem;
+ pSchema = pTab->pSchema;
+ /* Substitute the rowid (column -1) for the INTEGER PRIMARY KEY */
+ pExpr->iColumn = j==pTab->iPKey ? -1 : j;
+ if( i<pSrcList->nSrc-1 ){
+ if( pItem[1].jointype & JT_NATURAL ){
+ /* If this match occurred in the left table of a natural join,
+ ** then skip the right table to avoid a duplicate match */
+ pItem++;
+ i++;
+ }else if( (pUsing = pItem[1].pUsing)!=0 ){
+ /* If this match occurs on a column that is in the USING clause
+ ** of a join, skip the search of the right table of the join
+ ** to avoid a duplicate match there. */
+ int k;
+ for(k=0; k<pUsing->nId; k++){
+ if( sqlite3StrICmp(pUsing->a[k].zName, zCol)==0 ){
+ pItem++;
+ i++;
+ break;
+ }
+ }
+ }
+ }
+ break;
+ }
+ }
+ }
+ }
+
+#ifndef SQLITE_OMIT_TRIGGER
+ /* If we have not already resolved the name, then maybe
+ ** it is a new.* or old.* trigger argument reference
+ */
+ if( zDb==0 && zTab!=0 && cnt==0 && pParse->trigStack!=0 ){
+ TriggerStack *pTriggerStack = pParse->trigStack;
+ Table *pTab = 0;
+ u32 *piColMask;
+ if( pTriggerStack->newIdx != -1 && sqlite3StrICmp("new", zTab) == 0 ){
+ pExpr->iTable = pTriggerStack->newIdx;
+ assert( pTriggerStack->pTab );
+ pTab = pTriggerStack->pTab;
+ piColMask = &(pTriggerStack->newColMask);
+ }else if( pTriggerStack->oldIdx != -1 && sqlite3StrICmp("old", zTab)==0 ){
+ pExpr->iTable = pTriggerStack->oldIdx;
+ assert( pTriggerStack->pTab );
+ pTab = pTriggerStack->pTab;
+ piColMask = &(pTriggerStack->oldColMask);
+ }
+
+ if( pTab ){
+ int iCol;
+ Column *pCol = pTab->aCol;
+
+ pSchema = pTab->pSchema;
+ cntTab++;
+ for(iCol=0; iCol < pTab->nCol; iCol++, pCol++) {
+ if( sqlite3StrICmp(pCol->zName, zCol)==0 ){
+ cnt++;
+ pExpr->iColumn = iCol==pTab->iPKey ? -1 : iCol;
+ pExpr->pTab = pTab;
+ if( iCol>=0 ){
+ testcase( iCol==31 );
+ testcase( iCol==32 );
+ *piColMask |= ((u32)1<<iCol) | (iCol>=32?0xffffffff:0);
+ }
+ break;
+ }
+ }
+ }
+ }
+#endif /* !defined(SQLITE_OMIT_TRIGGER) */
+
+ /*
+ ** Perhaps the name is a reference to the ROWID
+ */
+ if( cnt==0 && cntTab==1 && sqlite3IsRowid(zCol) ){
+ cnt = 1;
+ pExpr->iColumn = -1;
+ pExpr->affinity = SQLITE_AFF_INTEGER;
+ }
+
+ /*
+ ** If the input is of the form Z (not Y.Z or X.Y.Z) then the name Z
+ ** might refer to an result-set alias. This happens, for example, when
+ ** we are resolving names in the WHERE clause of the following command:
+ **
+ ** SELECT a+b AS x FROM table WHERE x<10;
+ **
+ ** In cases like this, replace pExpr with a copy of the expression that
+ ** forms the result set entry ("a+b" in the example) and return immediately.
+ ** Note that the expression in the result set should have already been
+ ** resolved by the time the WHERE clause is resolved.
+ */
+ if( cnt==0 && (pEList = pNC->pEList)!=0 && zTab==0 ){
+ for(j=0; j<pEList->nExpr; j++){
+ char *zAs = pEList->a[j].zName;
+ if( zAs!=0 && sqlite3StrICmp(zAs, zCol)==0 ){
+ Expr *pOrig;
+ assert( pExpr->pLeft==0 && pExpr->pRight==0 );
+ assert( pExpr->pList==0 );
+ assert( pExpr->pSelect==0 );
+ pOrig = pEList->a[j].pExpr;
+ if( !pNC->allowAgg && ExprHasProperty(pOrig, EP_Agg) ){
+ sqlite3ErrorMsg(pParse, "misuse of aliased aggregate %s", zAs);
+ sqlite3DbFree(db, zCol);
+ return 2;
+ }
+ resolveAlias(pParse, pEList, j, pExpr, "");
+ cnt = 1;
+ pMatch = 0;
+ assert( zTab==0 && zDb==0 );
+ goto lookupname_end_2;
+ }
+ }
+ }
+
+ /* Advance to the next name context. The loop will exit when either
+ ** we have a match (cnt>0) or when we run out of name contexts.
+ */
+ if( cnt==0 ){
+ pNC = pNC->pNext;
+ }
+ }
+
+ /*
+ ** If X and Y are NULL (in other words if only the column name Z is
+ ** supplied) and the value of Z is enclosed in double-quotes, then
+ ** Z is a string literal if it doesn't match any column names. In that
+ ** case, we need to return right away and not make any changes to
+ ** pExpr.
+ **
+ ** Because no reference was made to outer contexts, the pNC->nRef
+ ** fields are not changed in any context.
+ */
+ if( cnt==0 && zTab==0 && pColumnToken->z[0]=='"' ){
+ sqlite3DbFree(db, zCol);
+ pExpr->op = TK_STRING;
+ return 0;
+ }
+
+ /*
+ ** cnt==0 means there was not match. cnt>1 means there were two or
+ ** more matches. Either way, we have an error.
+ */
+ if( cnt!=1 ){
+ const char *zErr;
+ zErr = cnt==0 ? "no such column" : "ambiguous column name";
+ if( zDb ){
+ sqlite3ErrorMsg(pParse, "%s: %s.%s.%s", zErr, zDb, zTab, zCol);
+ }else if( zTab ){
+ sqlite3ErrorMsg(pParse, "%s: %s.%s", zErr, zTab, zCol);
+ }else{
+ sqlite3ErrorMsg(pParse, "%s: %s", zErr, zCol);
+ }
+ pTopNC->nErr++;
+ }
+
+ /* If a column from a table in pSrcList is referenced, then record
+ ** this fact in the pSrcList.a[].colUsed bitmask. Column 0 causes
+ ** bit 0 to be set. Column 1 sets bit 1. And so forth. If the
+ ** column number is greater than the number of bits in the bitmask
+ ** then set the high-order bit of the bitmask.
+ */
+ if( pExpr->iColumn>=0 && pMatch!=0 ){
+ int n = pExpr->iColumn;
+ testcase( n==sizeof(Bitmask)*8-1 );
+ if( n>=sizeof(Bitmask)*8 ){
+ n = sizeof(Bitmask)*8-1;
+ }
+ assert( pMatch->iCursor==pExpr->iTable );
+ pMatch->colUsed |= ((Bitmask)1)<<n;
+ }
+
+lookupname_end:
+ /* Clean up and return
+ */
+ sqlite3DbFree(db, zDb);
+ sqlite3DbFree(db, zTab);
+ sqlite3ExprDelete(db, pExpr->pLeft);
+ pExpr->pLeft = 0;
+ sqlite3ExprDelete(db, pExpr->pRight);
+ pExpr->pRight = 0;
+ pExpr->op = TK_COLUMN;
+lookupname_end_2:
+ sqlite3DbFree(db, zCol);
+ if( cnt==1 ){
+ assert( pNC!=0 );
+ sqlite3AuthRead(pParse, pExpr, pSchema, pNC->pSrcList);
+ /* Increment the nRef value on all name contexts from TopNC up to
+ ** the point where the name matched. */
+ for(;;){
+ assert( pTopNC!=0 );
+ pTopNC->nRef++;
+ if( pTopNC==pNC ) break;
+ pTopNC = pTopNC->pNext;
+ }
+ return 0;
+ } else {
+ return 1;
+ }
+}
+
+/*
+** This routine is callback for sqlite3WalkExpr().
+**
+** Resolve symbolic names into TK_COLUMN operators for the current
+** node in the expression tree. Return 0 to continue the search down
+** the tree or 2 to abort the tree walk.
+**
+** This routine also does error checking and name resolution for
+** function names. The operator for aggregate functions is changed
+** to TK_AGG_FUNCTION.
+*/
+static int resolveExprStep(Walker *pWalker, Expr *pExpr){
+ NameContext *pNC;
+ Parse *pParse;
+
+ pNC = pWalker->u.pNC;
+ assert( pNC!=0 );
+ pParse = pNC->pParse;
+ assert( pParse==pWalker->pParse );
+
+ if( ExprHasAnyProperty(pExpr, EP_Resolved) ) return WRC_Prune;
+ ExprSetProperty(pExpr, EP_Resolved);
+#ifndef NDEBUG
+ if( pNC->pSrcList && pNC->pSrcList->nAlloc>0 ){
+ SrcList *pSrcList = pNC->pSrcList;
+ int i;
+ for(i=0; i<pNC->pSrcList->nSrc; i++){
+ assert( pSrcList->a[i].iCursor>=0 && pSrcList->a[i].iCursor<pParse->nTab);
+ }
+ }
+#endif
+ switch( pExpr->op ){
+
+#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
+ /* The special operator TK_ROW means use the rowid for the first
+ ** column in the FROM clause. This is used by the LIMIT and ORDER BY
+ ** clause processing on UPDATE and DELETE statements.
+ */
+ case TK_ROW: {
+ SrcList *pSrcList = pNC->pSrcList;
+ struct SrcList_item *pItem;
+ assert( pSrcList && pSrcList->nSrc==1 );
+ pItem = pSrcList->a;
+ pExpr->op = TK_COLUMN;
+ pExpr->pTab = pItem->pTab;
+ pExpr->iTable = pItem->iCursor;
+ pExpr->iColumn = -1;
+ pExpr->affinity = SQLITE_AFF_INTEGER;
+ break;
+ }
+#endif /* defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY) */
+
+ /* A lone identifier is the name of a column.
+ */
+ case TK_ID: {
+ lookupName(pParse, 0, 0, &pExpr->token, pNC, pExpr);
+ return WRC_Prune;
+ }
+
+ /* A table name and column name: ID.ID
+ ** Or a database, table and column: ID.ID.ID
+ */
+ case TK_DOT: {
+ Token *pColumn;
+ Token *pTable;
+ Token *pDb;
+ Expr *pRight;
+
+ /* if( pSrcList==0 ) break; */
+ pRight = pExpr->pRight;
+ if( pRight->op==TK_ID ){
+ pDb = 0;
+ pTable = &pExpr->pLeft->token;
+ pColumn = &pRight->token;
+ }else{
+ assert( pRight->op==TK_DOT );
+ pDb = &pExpr->pLeft->token;
+ pTable = &pRight->pLeft->token;
+ pColumn = &pRight->pRight->token;
+ }
+ lookupName(pParse, pDb, pTable, pColumn, pNC, pExpr);
+ return WRC_Prune;
+ }
+
+ /* Resolve function names
+ */
+ case TK_CONST_FUNC:
+ case TK_FUNCTION: {
+ ExprList *pList = pExpr->pList; /* The argument list */
+ int n = pList ? pList->nExpr : 0; /* Number of arguments */
+ int no_such_func = 0; /* True if no such function exists */
+ int wrong_num_args = 0; /* True if wrong number of arguments */
+ int is_agg = 0; /* True if is an aggregate function */
+ int auth; /* Authorization to use the function */
+ int nId; /* Number of characters in function name */
+ const char *zId; /* The function name. */
+ FuncDef *pDef; /* Information about the function */
+ int enc = ENC(pParse->db); /* The database encoding */
+
+ zId = (char*)pExpr->token.z;
+ nId = pExpr->token.n;
+ pDef = sqlite3FindFunction(pParse->db, zId, nId, n, enc, 0);
+ if( pDef==0 ){
+ pDef = sqlite3FindFunction(pParse->db, zId, nId, -1, enc, 0);
+ if( pDef==0 ){
+ no_such_func = 1;
+ }else{
+ wrong_num_args = 1;
+ }
+ }else{
+ is_agg = pDef->xFunc==0;
+ }
+#ifndef SQLITE_OMIT_AUTHORIZATION
+ if( pDef ){
+ auth = sqlite3AuthCheck(pParse, SQLITE_FUNCTION, 0, pDef->zName, 0);
+ if( auth!=SQLITE_OK ){
+ if( auth==SQLITE_DENY ){
+ sqlite3ErrorMsg(pParse, "not authorized to use function: %s",
+ pDef->zName);
+ pNC->nErr++;
+ }
+ pExpr->op = TK_NULL;
+ return WRC_Prune;
+ }
+ }
+#endif
+ if( is_agg && !pNC->allowAgg ){
+ sqlite3ErrorMsg(pParse, "misuse of aggregate function %.*s()", nId,zId);
+ pNC->nErr++;
+ is_agg = 0;
+ }else if( no_such_func ){
+ sqlite3ErrorMsg(pParse, "no such function: %.*s", nId, zId);
+ pNC->nErr++;
+ }else if( wrong_num_args ){
+ sqlite3ErrorMsg(pParse,"wrong number of arguments to function %.*s()",
+ nId, zId);
+ pNC->nErr++;
+ }
+ if( is_agg ){
+ pExpr->op = TK_AGG_FUNCTION;
+ pNC->hasAgg = 1;
+ }
+ if( is_agg ) pNC->allowAgg = 0;
+ sqlite3WalkExprList(pWalker, pList);
+ if( is_agg ) pNC->allowAgg = 1;
+ /* FIX ME: Compute pExpr->affinity based on the expected return
+ ** type of the function
+ */
+ return WRC_Prune;
+ }
+#ifndef SQLITE_OMIT_SUBQUERY
+ case TK_SELECT:
+ case TK_EXISTS:
+#endif
+ case TK_IN: {
+ if( pExpr->pSelect ){
+ int nRef = pNC->nRef;
+#ifndef SQLITE_OMIT_CHECK
+ if( pNC->isCheck ){
+ sqlite3ErrorMsg(pParse,"subqueries prohibited in CHECK constraints");
+ }
+#endif
+ sqlite3WalkSelect(pWalker, pExpr->pSelect);
+ assert( pNC->nRef>=nRef );
+ if( nRef!=pNC->nRef ){
+ ExprSetProperty(pExpr, EP_VarSelect);
+ }
+ }
+ break;
+ }
+#ifndef SQLITE_OMIT_CHECK
+ case TK_VARIABLE: {
+ if( pNC->isCheck ){
+ sqlite3ErrorMsg(pParse,"parameters prohibited in CHECK constraints");
+ }
+ break;
+ }
+#endif
+ }
+ return (pParse->nErr || pParse->db->mallocFailed) ? WRC_Abort : WRC_Continue;
+}
+
+/*
+** pEList is a list of expressions which are really the result set of the
+** a SELECT statement. pE is a term in an ORDER BY or GROUP BY clause.
+** This routine checks to see if pE is a simple identifier which corresponds
+** to the AS-name of one of the terms of the expression list. If it is,
+** this routine return an integer between 1 and N where N is the number of
+** elements in pEList, corresponding to the matching entry. If there is
+** no match, or if pE is not a simple identifier, then this routine
+** return 0.
+**
+** pEList has been resolved. pE has not.
+*/
+static int resolveAsName(
+ Parse *pParse, /* Parsing context for error messages */
+ ExprList *pEList, /* List of expressions to scan */
+ Expr *pE /* Expression we are trying to match */
+){
+ int i; /* Loop counter */
+
+ if( pE->op==TK_ID || (pE->op==TK_STRING && pE->token.z[0]!='\'') ){
+ sqlite3 *db = pParse->db;
+ char *zCol = sqlite3NameFromToken(db, &pE->token);
+ if( zCol==0 ){
+ return -1;
+ }
+ for(i=0; i<pEList->nExpr; i++){
+ char *zAs = pEList->a[i].zName;
+ if( zAs!=0 && sqlite3StrICmp(zAs, zCol)==0 ){
+ sqlite3DbFree(db, zCol);
+ return i+1;
+ }
+ }
+ sqlite3DbFree(db, zCol);
+ }
+ return 0;
+}
+
+/*
+** pE is a pointer to an expression which is a single term in the
+** ORDER BY of a compound SELECT. The expression has not been
+** name resolved.
+**
+** At the point this routine is called, we already know that the
+** ORDER BY term is not an integer index into the result set. That
+** case is handled by the calling routine.
+**
+** Attempt to match pE against result set columns in the left-most
+** SELECT statement. Return the index i of the matching column,
+** as an indication to the caller that it should sort by the i-th column.
+** The left-most column is 1. In other words, the value returned is the
+** same integer value that would be used in the SQL statement to indicate
+** the column.
+**
+** If there is no match, return 0. Return -1 if an error occurs.
+*/
+static int resolveOrderByTermToExprList(
+ Parse *pParse, /* Parsing context for error messages */
+ Select *pSelect, /* The SELECT statement with the ORDER BY clause */
+ Expr *pE /* The specific ORDER BY term */
+){
+ int i; /* Loop counter */
+ ExprList *pEList; /* The columns of the result set */
+ NameContext nc; /* Name context for resolving pE */
+
+ assert( sqlite3ExprIsInteger(pE, &i)==0 );
+ pEList = pSelect->pEList;
+
+ /* Resolve all names in the ORDER BY term expression
+ */
+ memset(&nc, 0, sizeof(nc));
+ nc.pParse = pParse;
+ nc.pSrcList = pSelect->pSrc;
+ nc.pEList = pEList;
+ nc.allowAgg = 1;
+ nc.nErr = 0;
+ if( sqlite3ResolveExprNames(&nc, pE) ){
+ sqlite3ErrorClear(pParse);
+ return 0;
+ }
+
+ /* Try to match the ORDER BY expression against an expression
+ ** in the result set. Return an 1-based index of the matching
+ ** result-set entry.
+ */
+ for(i=0; i<pEList->nExpr; i++){
+ if( sqlite3ExprCompare(pEList->a[i].pExpr, pE) ){
+ return i+1;
+ }
+ }
+
+ /* If no match, return 0. */
+ return 0;
+}
+
+/*
+** Generate an ORDER BY or GROUP BY term out-of-range error.
+*/
+static void resolveOutOfRangeError(
+ Parse *pParse, /* The error context into which to write the error */
+ const char *zType, /* "ORDER" or "GROUP" */
+ int i, /* The index (1-based) of the term out of range */
+ int mx /* Largest permissible value of i */
+){
+ sqlite3ErrorMsg(pParse,
+ "%r %s BY term out of range - should be "
+ "between 1 and %d", i, zType, mx);
+}
+
+/*
+** Analyze the ORDER BY clause in a compound SELECT statement. Modify
+** each term of the ORDER BY clause is a constant integer between 1
+** and N where N is the number of columns in the compound SELECT.
+**
+** ORDER BY terms that are already an integer between 1 and N are
+** unmodified. ORDER BY terms that are integers outside the range of
+** 1 through N generate an error. ORDER BY terms that are expressions
+** are matched against result set expressions of compound SELECT
+** beginning with the left-most SELECT and working toward the right.
+** At the first match, the ORDER BY expression is transformed into
+** the integer column number.
+**
+** Return the number of errors seen.
+*/
+static int resolveCompoundOrderBy(
+ Parse *pParse, /* Parsing context. Leave error messages here */
+ Select *pSelect /* The SELECT statement containing the ORDER BY */
+){
+ int i;
+ ExprList *pOrderBy;
+ ExprList *pEList;
+ sqlite3 *db;
+ int moreToDo = 1;
+
+ pOrderBy = pSelect->pOrderBy;
+ if( pOrderBy==0 ) return 0;
+ db = pParse->db;
+#if SQLITE_MAX_COLUMN
+ if( pOrderBy->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){
+ sqlite3ErrorMsg(pParse, "too many terms in ORDER BY clause");
+ return 1;
+ }
+#endif
+ for(i=0; i<pOrderBy->nExpr; i++){
+ pOrderBy->a[i].done = 0;
+ }
+ pSelect->pNext = 0;
+ while( pSelect->pPrior ){
+ pSelect->pPrior->pNext = pSelect;
+ pSelect = pSelect->pPrior;
+ }
+ while( pSelect && moreToDo ){
+ struct ExprList_item *pItem;
+ moreToDo = 0;
+ pEList = pSelect->pEList;
+ assert( pEList!=0 );
+ for(i=0, pItem=pOrderBy->a; i<pOrderBy->nExpr; i++, pItem++){
+ int iCol = -1;
+ Expr *pE, *pDup;
+ if( pItem->done ) continue;
+ pE = pItem->pExpr;
+ if( sqlite3ExprIsInteger(pE, &iCol) ){
+ if( iCol<0 || iCol>pEList->nExpr ){
+ resolveOutOfRangeError(pParse, "ORDER", i+1, pEList->nExpr);
+ return 1;
+ }
+ }else{
+ iCol = resolveAsName(pParse, pEList, pE);
+ if( iCol==0 ){
+ pDup = sqlite3ExprDup(db, pE);
+ if( !db->mallocFailed ){
+ assert(pDup);
+ iCol = resolveOrderByTermToExprList(pParse, pSelect, pDup);
+ }
+ sqlite3ExprDelete(db, pDup);
+ }
+ if( iCol<0 ){
+ return 1;
+ }
+ }
+ if( iCol>0 ){
+ CollSeq *pColl = pE->pColl;
+ int flags = pE->flags & EP_ExpCollate;
+ sqlite3ExprDelete(db, pE);
+ pItem->pExpr = pE = sqlite3Expr(db, TK_INTEGER, 0, 0, 0);
+ if( pE==0 ) return 1;
+ pE->pColl = pColl;
+ pE->flags |= EP_IntValue | flags;
+ pE->iTable = iCol;
+ pItem->iCol = iCol;
+ pItem->done = 1;
+ }else{
+ moreToDo = 1;
+ }
+ }
+ pSelect = pSelect->pNext;
+ }
+ for(i=0; i<pOrderBy->nExpr; i++){
+ if( pOrderBy->a[i].done==0 ){
+ sqlite3ErrorMsg(pParse, "%r ORDER BY term does not match any "
+ "column in the result set", i+1);
+ return 1;
+ }
+ }
+ return 0;
+}
+
+/*
+** Check every term in the ORDER BY or GROUP BY clause pOrderBy of
+** the SELECT statement pSelect. If any term is reference to a
+** result set expression (as determined by the ExprList.a.iCol field)
+** then convert that term into a copy of the corresponding result set
+** column.
+**
+** If any errors are detected, add an error message to pParse and
+** return non-zero. Return zero if no errors are seen.
+*/
+int sqlite3ResolveOrderGroupBy(
+ Parse *pParse, /* Parsing context. Leave error messages here */
+ Select *pSelect, /* The SELECT statement containing the clause */
+ ExprList *pOrderBy, /* The ORDER BY or GROUP BY clause to be processed */
+ const char *zType /* "ORDER" or "GROUP" */
+){
+ int i;
+ sqlite3 *db = pParse->db;
+ ExprList *pEList;
+ struct ExprList_item *pItem;
+
+ if( pOrderBy==0 || pParse->db->mallocFailed ) return 0;
+#if SQLITE_MAX_COLUMN
+ if( pOrderBy->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){
+ sqlite3ErrorMsg(pParse, "too many terms in %s BY clause", zType);
+ return 1;
+ }
+#endif
+ pEList = pSelect->pEList;
+ assert( pEList!=0 ); /* sqlite3SelectNew() guarantees this */
+ for(i=0, pItem=pOrderBy->a; i<pOrderBy->nExpr; i++, pItem++){
+ if( pItem->iCol ){
+ if( pItem->iCol>pEList->nExpr ){
+ resolveOutOfRangeError(pParse, zType, i+1, pEList->nExpr);
+ return 1;
+ }
+ resolveAlias(pParse, pEList, pItem->iCol-1, pItem->pExpr, zType);
+ }
+ }
+ return 0;
+}
+
+/*
+** pOrderBy is an ORDER BY or GROUP BY clause in SELECT statement pSelect.
+** The Name context of the SELECT statement is pNC. zType is either
+** "ORDER" or "GROUP" depending on which type of clause pOrderBy is.
+**
+** This routine resolves each term of the clause into an expression.
+** If the order-by term is an integer I between 1 and N (where N is the
+** number of columns in the result set of the SELECT) then the expression
+** in the resolution is a copy of the I-th result-set expression. If
+** the order-by term is an identify that corresponds to the AS-name of
+** a result-set expression, then the term resolves to a copy of the
+** result-set expression. Otherwise, the expression is resolved in
+** the usual way - using sqlite3ResolveExprNames().
+**
+** This routine returns the number of errors. If errors occur, then
+** an appropriate error message might be left in pParse. (OOM errors
+** excepted.)
+*/
+static int resolveOrderGroupBy(
+ NameContext *pNC, /* The name context of the SELECT statement */
+ Select *pSelect, /* The SELECT statement holding pOrderBy */
+ ExprList *pOrderBy, /* An ORDER BY or GROUP BY clause to resolve */
+ const char *zType /* Either "ORDER" or "GROUP", as appropriate */
+){
+ int i; /* Loop counter */
+ int iCol; /* Column number */
+ struct ExprList_item *pItem; /* A term of the ORDER BY clause */
+ Parse *pParse; /* Parsing context */
+ int nResult; /* Number of terms in the result set */
+
+ if( pOrderBy==0 ) return 0;
+ nResult = pSelect->pEList->nExpr;
+ pParse = pNC->pParse;
+ for(i=0, pItem=pOrderBy->a; i<pOrderBy->nExpr; i++, pItem++){
+ Expr *pE = pItem->pExpr;
+ iCol = resolveAsName(pParse, pSelect->pEList, pE);
+ if( iCol<0 ){
+ return 1; /* OOM error */
+ }
+ if( iCol>0 ){
+ /* If an AS-name match is found, mark this ORDER BY column as being
+ ** a copy of the iCol-th result-set column. The subsequent call to
+ ** sqlite3ResolveOrderGroupBy() will convert the expression to a
+ ** copy of the iCol-th result-set expression. */
+ pItem->iCol = iCol;
+ continue;
+ }
+ if( sqlite3ExprIsInteger(pE, &iCol) ){
+ /* The ORDER BY term is an integer constant. Again, set the column
+ ** number so that sqlite3ResolveOrderGroupBy() will convert the
+ ** order-by term to a copy of the result-set expression */
+ if( iCol<1 ){
+ resolveOutOfRangeError(pParse, zType, i+1, nResult);
+ return 1;
+ }
+ pItem->iCol = iCol;
+ continue;
+ }
+
+ /* Otherwise, treat the ORDER BY term as an ordinary expression */
+ pItem->iCol = 0;
+ if( sqlite3ResolveExprNames(pNC, pE) ){
+ return 1;
+ }
+ }
+ return sqlite3ResolveOrderGroupBy(pParse, pSelect, pOrderBy, zType);
+}
+
+/*
+** Resolve names in the SELECT statement p and all of its descendents.
+*/
+static int resolveSelectStep(Walker *pWalker, Select *p){
+ NameContext *pOuterNC; /* Context that contains this SELECT */
+ NameContext sNC; /* Name context of this SELECT */
+ int isCompound; /* True if p is a compound select */
+ int nCompound; /* Number of compound terms processed so far */
+ Parse *pParse; /* Parsing context */
+ ExprList *pEList; /* Result set expression list */
+ int i; /* Loop counter */
+ ExprList *pGroupBy; /* The GROUP BY clause */
+ Select *pLeftmost; /* Left-most of SELECT of a compound */
+ sqlite3 *db; /* Database connection */
+
+
+ assert( p!=0 );
+ if( p->selFlags & SF_Resolved ){
+ return WRC_Prune;
+ }
+ pOuterNC = pWalker->u.pNC;
+ pParse = pWalker->pParse;
+ db = pParse->db;
+
+ /* Normally sqlite3SelectExpand() will be called first and will have
+ ** already expanded this SELECT. However, if this is a subquery within
+ ** an expression, sqlite3ResolveExprNames() will be called without a
+ ** prior call to sqlite3SelectExpand(). When that happens, let
+ ** sqlite3SelectPrep() do all of the processing for this SELECT.
+ ** sqlite3SelectPrep() will invoke both sqlite3SelectExpand() and
+ ** this routine in the correct order.
+ */
+ if( (p->selFlags & SF_Expanded)==0 ){
+ sqlite3SelectPrep(pParse, p, pOuterNC);
+ return (pParse->nErr || db->mallocFailed) ? WRC_Abort : WRC_Prune;
+ }
+
+ isCompound = p->pPrior!=0;
+ nCompound = 0;
+ pLeftmost = p;
+ while( p ){
+ assert( (p->selFlags & SF_Expanded)!=0 );
+ assert( (p->selFlags & SF_Resolved)==0 );
+ p->selFlags |= SF_Resolved;
+
+ /* 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( sqlite3ResolveExprNames(&sNC, p->pLimit) ||
+ sqlite3ResolveExprNames(&sNC, p->pOffset) ){
+ return WRC_Abort;
+ }
+
+ /* Set up the local name-context to pass to sqlite3ResolveExprNames() to
+ ** resolve the result-set expression list.
+ */
+ sNC.allowAgg = 1;
+ sNC.pSrcList = p->pSrc;
+ sNC.pNext = pOuterNC;
+
+ /* Resolve names in the result set. */
+ pEList = p->pEList;
+ assert( pEList!=0 );
+ for(i=0; i<pEList->nExpr; i++){
+ Expr *pX = pEList->a[i].pExpr;
+ if( sqlite3ResolveExprNames(&sNC, pX) ){
+ return WRC_Abort;
+ }
+ }
+
+ /* Recursively resolve names in all subqueries
+ */
+ for(i=0; i<p->pSrc->nSrc; i++){
+ struct SrcList_item *pItem = &p->pSrc->a[i];
+ if( pItem->pSelect ){
+ const char *zSavedContext = pParse->zAuthContext;
+ if( pItem->zName ) pParse->zAuthContext = pItem->zName;
+ sqlite3ResolveSelectNames(pParse, pItem->pSelect, &sNC);
+ pParse->zAuthContext = zSavedContext;
+ if( pParse->nErr || db->mallocFailed ) return WRC_Abort;
+ }
+ }
+
+ /* 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->selFlags & SF_Aggregate)==0 );
+ pGroupBy = p->pGroupBy;
+ if( pGroupBy || sNC.hasAgg ){
+ p->selFlags |= SF_Aggregate;
+ }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 WRC_Abort;
+ }
+
+ /* 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( sqlite3ResolveExprNames(&sNC, p->pWhere) ||
+ sqlite3ResolveExprNames(&sNC, p->pHaving)
+ ){
+ return WRC_Abort;
+ }
+
+ /* The ORDER BY and GROUP BY clauses may not refer to terms in
+ ** outer queries
+ */
+ sNC.pNext = 0;
+ sNC.allowAgg = 1;
+
+ /* Process the ORDER BY clause for singleton SELECT statements.
+ ** The ORDER BY clause for compounds SELECT statements is handled
+ ** below, after all of the result-sets for all of the elements of
+ ** the compound have been resolved.
+ */
+ if( !isCompound && resolveOrderGroupBy(&sNC, p, p->pOrderBy, "ORDER") ){
+ return WRC_Abort;
+ }
+ if( db->mallocFailed ){
+ return WRC_Abort;
+ }
+
+ /* Resolve the GROUP BY clause. At the same time, make sure
+ ** the GROUP BY clause does not contain aggregate functions.
+ */
+ if( pGroupBy ){
+ struct ExprList_item *pItem;
+
+ if( resolveOrderGroupBy(&sNC, p, pGroupBy, "GROUP") || db->mallocFailed ){
+ return WRC_Abort;
+ }
+ 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 WRC_Abort;
+ }
+ }
+ }
+
+ /* Advance to the next term of the compound
+ */
+ p = p->pPrior;
+ nCompound++;
+ }
+
+ /* Resolve the ORDER BY on a compound SELECT after all terms of
+ ** the compound have been resolved.
+ */
+ if( isCompound && resolveCompoundOrderBy(pParse, pLeftmost) ){
+ return WRC_Abort;
+ }
+
+ return WRC_Prune;
+}
+
+/*
+** This routine walks an expression tree and resolves references to
+** table columns and result-set columns. At the same time, do error
+** checking on function usage and set a flag if any aggregate functions
+** are seen.
+**
+** To resolve table columns references we look for nodes (or subtrees) of the
+** form X.Y.Z or Y.Z or just Z where
+**
+** X: The name of a database. Ex: "main" or "temp" or
+** the symbolic name assigned to an ATTACH-ed database.
+**
+** Y: The name of a table in a FROM clause. Or in a trigger
+** one of the special names "old" or "new".
+**
+** Z: The name of a column in table Y.
+**
+** The node at the root of the subtree is modified as follows:
+**
+** Expr.op Changed to TK_COLUMN
+** Expr.pTab Points to the Table object for X.Y
+** Expr.iColumn The column index in X.Y. -1 for the rowid.
+** Expr.iTable The VDBE cursor number for X.Y
+**
+**
+** To resolve result-set references, look for expression nodes of the
+** form Z (with no X and Y prefix) where the Z matches the right-hand
+** size of an AS clause in the result-set of a SELECT. The Z expression
+** is replaced by a copy of the left-hand side of the result-set expression.
+** Table-name and function resolution occurs on the substituted expression
+** tree. For example, in:
+**
+** SELECT a+b AS x, c+d AS y FROM t1 ORDER BY x;
+**
+** The "x" term of the order by is replaced by "a+b" to render:
+**
+** SELECT a+b AS x, c+d AS y FROM t1 ORDER BY a+b;
+**
+** Function calls are checked to make sure that the function is
+** defined and that the correct number of arguments are specified.
+** If the function is an aggregate function, then the pNC->hasAgg is
+** set and the opcode is changed from TK_FUNCTION to TK_AGG_FUNCTION.
+** If an expression contains aggregate functions then the EP_Agg
+** property on the expression is set.
+**
+** An error message is left in pParse if anything is amiss. The number
+** if errors is returned.
+*/
+int sqlite3ResolveExprNames(
+ NameContext *pNC, /* Namespace to resolve expressions in. */
+ Expr *pExpr /* The expression to be analyzed. */
+){
+ int savedHasAgg;
+ Walker w;
+
+ if( pExpr==0 ) return 0;
+#if SQLITE_MAX_EXPR_DEPTH>0
+ {
+ Parse *pParse = pNC->pParse;
+ if( sqlite3ExprCheckHeight(pParse, pExpr->nHeight+pNC->pParse->nHeight) ){
+ return 1;
+ }
+ pParse->nHeight += pExpr->nHeight;
+ }
+#endif
+ savedHasAgg = pNC->hasAgg;
+ pNC->hasAgg = 0;
+ w.xExprCallback = resolveExprStep;
+ w.xSelectCallback = resolveSelectStep;
+ w.pParse = pNC->pParse;
+ w.u.pNC = pNC;
+ sqlite3WalkExpr(&w, pExpr);
+#if SQLITE_MAX_EXPR_DEPTH>0
+ pNC->pParse->nHeight -= pExpr->nHeight;
+#endif
+ if( pNC->nErr>0 ){
+ ExprSetProperty(pExpr, EP_Error);
+ }
+ if( pNC->hasAgg ){
+ ExprSetProperty(pExpr, EP_Agg);
+ }else if( savedHasAgg ){
+ pNC->hasAgg = 1;
+ }
+ return ExprHasProperty(pExpr, EP_Error);
+}
+
+
+/*
+** Resolve all names in all expressions of a SELECT and in all
+** decendents of the SELECT, including compounds off of p->pPrior,
+** subqueries in expressions, and subqueries used as FROM clause
+** terms.
+**
+** See sqlite3ResolveExprNames() for a description of the kinds of
+** transformations that occur.
+**
+** All SELECT statements should have been expanded using
+** sqlite3SelectExpand() prior to invoking this routine.
+*/
+void sqlite3ResolveSelectNames(
+ Parse *pParse, /* The parser context */
+ Select *p, /* The SELECT statement being coded. */
+ NameContext *pOuterNC /* Name context for parent SELECT statement */
+){
+ Walker w;
+
+ assert( p!=0 );
+ w.xExprCallback = resolveExprStep;
+ w.xSelectCallback = resolveSelectStep;
+ w.pParse = pParse;
+ w.u.pNC = pOuterNC;
+ sqlite3WalkSelect(&w, p);
+}