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Diffstat (limited to 'kexi/3rdparty/kexisql3/src/select.c')
| -rw-r--r-- | kexi/3rdparty/kexisql3/src/select.c | 3127 |
1 files changed, 3127 insertions, 0 deletions
diff --git a/kexi/3rdparty/kexisql3/src/select.c b/kexi/3rdparty/kexisql3/src/select.c new file mode 100644 index 00000000..86b22c38 --- /dev/null +++ b/kexi/3rdparty/kexisql3/src/select.c @@ -0,0 +1,3127 @@ +/* +** 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 548347 2006-06-05 10:53:00Z staniek $ +*/ +#include "sqliteInt.h" + + +/* +** 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; + pNew = sqliteMalloc( sizeof(*pNew) ); + assert( !pOffset || pLimit ); /* Can't have OFFSET without LIMIT. */ + if( pNew==0 ){ + sqlite3ExprListDelete(pEList); + sqlite3SrcListDelete(pSrc); + sqlite3ExprDelete(pWhere); + sqlite3ExprListDelete(pGroupBy); + sqlite3ExprDelete(pHaving); + sqlite3ExprListDelete(pOrderBy); + sqlite3ExprDelete(pLimit); + sqlite3ExprDelete(pOffset); + }else{ + 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->addrOpenVirt[0] = -1; + pNew->addrOpenVirt[1] = -1; + pNew->addrOpenVirt[2] = -1; + } + return pNew; +} + +/* +** 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(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 = z; + p->n = strlen(z); + p->dyn = 0; +} + +/* +** Create an expression node for an identifier with the name of zName +*/ +static Expr *createIdExpr(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 = createIdExpr(zCol); + pE2a = createIdExpr(zCol); + if( zAlias1==0 ){ + zAlias1 = pTab1->zName; + } + pE1b = createIdExpr(zAlias1); + if( zAlias2==0 ){ + zAlias2 = pTab2->zName; + } + pE2b = createIdExpr(zAlias2); + pE1c = sqlite3Expr(TK_DOT, pE1b, pE1a, 0); + pE2c = sqlite3Expr(TK_DOT, pE2b, pE2a, 0); + pE = sqlite3Expr(TK_EQ, pE1c, pE2c, 0); + ExprSetProperty(pE, EP_FromJoin); + pE->iRightJoinTable = iRightJoinTable; + *ppExpr = sqlite3ExprAnd(*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; +} + +/* +** Delete the given Select structure and all of its substructures. +*/ +void sqlite3SelectDelete(Select *p){ + if( p==0 ) return; + 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); + sqliteFree(p); +} + +/* +** Insert code into "v" that will push the record on the top of the +** stack into the sorter. +*/ +static void pushOntoSorter(Parse *pParse, Vdbe *v, ExprList *pOrderBy){ + 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); +} + +/* +** Add code to implement the OFFSET and LIMIT +*/ +static void codeLimiter( + Vdbe *v, /* Generate code into this VM */ + Select *p, /* The SELECT statement being coded */ + int iContinue, /* Jump here to skip the current record */ + int iBreak, /* Jump here to end the loop */ + int nPop /* Number of times to pop stack when jumping */ +){ + if( p->iOffset>=0 && iContinue!=0 ){ + int addr = sqlite3VdbeCurrentAddr(v) + 3; + if( nPop>0 ) addr++; + sqlite3VdbeAddOp(v, OP_MemIncr, p->iOffset, 0); + sqlite3VdbeAddOp(v, OP_IfMemPos, p->iOffset, addr); + if( nPop>0 ){ + sqlite3VdbeAddOp(v, OP_Pop, nPop, 0); + } + sqlite3VdbeAddOp(v, OP_Goto, 0, iContinue); + VdbeComment((v, "# skip OFFSET records")); + } + if( p->iLimit>=0 && iBreak!=0 ){ + sqlite3VdbeAddOp(v, OP_MemIncr, p->iLimit, iBreak); + VdbeComment((v, "# exit when LIMIT reached")); + } +} + +/* +** 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 K 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 */ + int K /* Pop K elements from the stack if indistinct */ +){ +#if NULL_ALWAYS_DISTINCT + sqlite3VdbeAddOp(v, OP_IsNull, -N, sqlite3VdbeCurrentAddr(v)+6); +#endif + sqlite3VdbeAddOp(v, OP_MakeRecord, -N, 0); + sqlite3VdbeAddOp(v, OP_Distinct, iTab, sqlite3VdbeCurrentAddr(v)+3); + sqlite3VdbeAddOp(v, OP_Pop, K, 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 && pEList->nExpr>0; + if( pOrderBy==0 && !hasDistinct ){ + codeLimiter(v, p, iContinue, iBreak, 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 ){ + int n = pEList->nExpr; + codeDistinct(v, distinct, iContinue, n, n+1); + if( pOrderBy==0 ){ + codeLimiter(v, p, iContinue, iBreak, 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, NULL_ALWAYS_DISTINCT); + 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, NULL_ALWAYS_DISTINCT); + 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_VirtualTab: { + sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0); + if( pOrderBy ){ + pushOntoSorter(pParse, v, pOrderBy); + }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, v, pOrderBy); + }else{ + char aff = (iParm>>16)&0xFF; + aff = sqlite3CompareAffinity(pEList->a[0].pExpr, aff); + sqlite3VdbeOp3(v, OP_MakeRecord, 1, 0, &aff, 1); + sqlite3VdbeAddOp(v, OP_IdxInsert, (iParm&0x0000FFFF), 0); + } + sqlite3VdbeJumpHere(v, addr2); + 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_Exists: + case SRT_Mem: { + assert( nColumn==1 ); + if( pOrderBy ){ + pushOntoSorter(pParse, v, pOrderBy); + }else{ + sqlite3VdbeAddOp(v, OP_MemStore, iParm, 1); + sqlite3VdbeAddOp(v, OP_Goto, 0, iBreak); + } + 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, v, pOrderBy); + }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 + } + 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 = (char*)&pInfo->aColl[nExpr]; + pInfo->nField = nExpr; + pInfo->enc = db->enc; + 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, /* The 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; + ExprList *pOrderBy = p->pOrderBy; + + iTab = pOrderBy->iECursor; + addr = 1 + sqlite3VdbeAddOp(v, OP_Sort, iTab, brk); + codeLimiter(v, p, cont, brk, 0); + sqlite3VdbeAddOp(v, OP_Column, iTab, pOrderBy->nExpr + 1); + switch( eDest ){ + case SRT_Table: + case SRT_VirtualTab: { + 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, "n", P3_STATIC); + sqlite3VdbeAddOp(v, OP_IdxInsert, (iParm&0x0000FFFF), 0); + break; + } + case SRT_Exists: + case SRT_Mem: { + assert( nColumn==1 ); + sqlite3VdbeAddOp(v, OP_MemStore, iParm, 1); + sqlite3VdbeAddOp(v, OP_Goto, 0, brk); + break; + } +#endif + case SRT_Callback: + case SRT_Subroutine: { + int i; + sqlite3VdbeAddOp(v, OP_Integer, p->pEList->nExpr, 0); + sqlite3VdbeAddOp(v, OP_Pull, 1, 0); + for(i=0; i<nColumn; i++){ + sqlite3VdbeAddOp(v, OP_Column, -1-i, i); + } + if( eDest==SRT_Callback ){ + sqlite3VdbeAddOp(v, OP_Callback, nColumn, 0); + }else{ + sqlite3VdbeAddOp(v, OP_Gosub, 0, iParm); + } + sqlite3VdbeAddOp(v, OP_Pop, 2, 0); + break; + } + default: { + /* Do nothing */ + break; + } + } + sqlite3VdbeResolveLabel(v, cont); + sqlite3VdbeAddOp(v, OP_Next, iTab, addr); + sqlite3VdbeResolveLabel(v, brk); +} + +/* +** Return a pointer to a string containing the 'declaration type' of the +** expression pExpr. The string may be treated as static by the caller. +** +** If 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 an expression is either TEXT, NUMERIC or ANY. +** The declaration type for a ROWID field is INTEGER. +*/ +static const char *columnType(NameContext *pNC, Expr *pExpr){ + char const *zType; + 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_COLUMN: { + Table *pTab = 0; + int iCol = pExpr->iColumn; + 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; + }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( iCol<0 ) iCol = pTab->iPKey; + assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) ); + if( iCol<0 ){ + zType = "INTEGER"; + }else{ + zType = pTab->aCol[iCol].zType; + } + break; + } +#ifndef SQLITE_OMIT_SUBQUERY + case TK_SELECT: { + NameContext sNC; + Select *pS = pExpr->pSelect; + sNC.pSrcList = pExpr->pSelect->pSrc; + sNC.pNext = pNC; + zType = columnType(&sNC, pS->pEList->a[0].pExpr); + break; + } +#endif + default: + zType = 0; + } + + 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; + for(i=0; i<pEList->nExpr; i++){ + Expr *p = pEList->a[i].pExpr; + const char *zType = columnType(&sNC, p); + if( zType==0 ) continue; + /* The vdbe must make it's own copy of the column-type, in case the + ** schema is reset before this virtual machine is deleted. + */ + sqlite3VdbeSetColName(v, i+pEList->nExpr, zType, strlen(zType)); + } +} + +/* +** 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 || sqlite3_malloc_failed ) 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, 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, 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, 0); + sqlite3VdbeSetColName(v, i, zName, P3_DYNAMIC); + }else{ + sqlite3VdbeSetColName(v, i, zCol, strlen(zCol)); + } + }else if( p->span.z && p->span.z[0] ){ + sqlite3VdbeSetColName(v, i, 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, 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; + + 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; + 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( sqlite3_malloc_failed ){ + 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)); + pCol->zType = zType; + pCol->affinity = sqlite3ExprAffinity(p); + pCol->pColl = sqlite3ExprCollSeq(pParse, p); + if( !pCol->pColl ){ + pCol->pColl = pParse->db->pDfltColl; + } + } + 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; + Table *pTab; + struct SrcList_item *pFrom; + + if( p==0 || p->pSrc==0 || sqlite3_malloc_failed ) 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++){ + 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 isTransient 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->isTransient = 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++; +#ifndef SQLITE_OMIT_VIEW + if( pTab->pSelect ){ + /* 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); + pNew->a[pNew->nExpr-1].zName = a[k].zName; + 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, *pLeft, *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) ){ + 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. nLimit and nOffset 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 if iLimit and iOffset only if +** a limit or offset is defined by nLimit and nOffset. iLimit and +** iOffset should have been preset to appropriate default values +** (usually but not always -1) prior to calling this routine. +** Only if nLimit>=0 or nOffset>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){ + /* + ** "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 ){ + int iMem = pParse->nMem++; + Vdbe *v = sqlite3GetVdbe(pParse); + if( v==0 ) return; + sqlite3ExprCode(pParse, p->pLimit); + sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0); + sqlite3VdbeAddOp(v, OP_Negative, 0, 0); + sqlite3VdbeAddOp(v, OP_MemStore, iMem, 1); + VdbeComment((v, "# LIMIT counter")); + p->iLimit = iMem; + } + if( p->pOffset ){ + int iMem = pParse->nMem++; + Vdbe *v = sqlite3GetVdbe(pParse); + if( v==0 ) return; + sqlite3ExprCode(pParse, p->pOffset); + sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0); + sqlite3VdbeAddOp(v, OP_Negative, 0, 0); + sqlite3VdbeAddOp(v, OP_MemStore, iMem, 1); + VdbeComment((v, "# OFFSET counter")); + p->iOffset = iMem; + } +} + +/* +** 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_OpenVirtual, + pOrderBy->iECursor, pOrderBy->nExpr+1); + assert( p->addrOpenVirt[2] == -1 ); + p->addrOpenVirt[2] = addr; + } +} + +/* +** The opcode at addr is an OP_OpenVirtual that created a sorting +** index tha we ended up not needing. This routine changes that +** opcode to OP_Noop. +*/ +static void uncreateSortingIndex(Parse *pParse, int addr){ + Vdbe *v = pParse->pVdbe; + VdbeOp *pOp = sqlite3VdbeGetOp(v, addr); + sqlite3VdbeChangeP3(v, addr, 0, 0); + pOp->opcode = OP_Noop; + pOp->p1 = 0; + pOp->p2 = 0; +} + +#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_VirtualTab ){ + assert( p->pEList ); + assert( nSetP2<sizeof(aSetP2)/sizeof(aSetP2[0]) ); + aSetP2[nSetP2++] = sqlite3VdbeAddOp(v, OP_OpenVirtual, 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 ){ + assert( !pPrior->pLimit ); + pPrior->pLimit = p->pLimit; + pPrior->pOffset = p->pOffset; + rc = sqlite3Select(pParse, pPrior, eDest, iParm, 0, 0, 0, aff); + if( rc ){ + goto multi_select_end; + } + p->pPrior = 0; + p->iLimit = pPrior->iLimit; + p->iOffset = pPrior->iOffset; + p->pLimit = 0; + p->pOffset = 0; + rc = sqlite3Select(pParse, p, eDest, iParm, 0, 0, 0, aff); + p->pPrior = pPrior; + if( rc ){ + goto multi_select_end; + } + 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_OpenVirtual, unionTab, 0); + if( priorOp==SRT_Table ){ + assert( nSetP2<sizeof(aSetP2)/sizeof(aSetP2[0]) ); + aSetP2[nSetP2++] = addr; + }else{ + assert( p->addrOpenVirt[0] == -1 ); + p->addrOpenVirt[0] = addr; + p->pRightmost->usesVirt = 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 ){ + generateColumnNames(pParse, 0, p->pEList); + } + iBreak = sqlite3VdbeMakeLabel(v); + iCont = sqlite3VdbeMakeLabel(v); + sqlite3VdbeAddOp(v, OP_Rewind, unionTab, iBreak); + computeLimitRegisters(pParse, p); + 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_OpenVirtual, tab1, 0); + assert( p->addrOpenVirt[0] == -1 ); + p->addrOpenVirt[0] = addr; + p->pRightmost->usesVirt = 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_OpenVirtual, tab2, 0); + assert( p->addrOpenVirt[1] == -1 ); + p->addrOpenVirt[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 ){ + generateColumnNames(pParse, 0, p->pEList); + } + iBreak = sqlite3VdbeMakeLabel(v); + iCont = sqlite3VdbeMakeLabel(v); + sqlite3VdbeAddOp(v, OP_Rewind, tab1, iBreak); + computeLimitRegisters(pParse, p); + 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->usesVirt ){ + int i; /* Loop counter */ + KeyInfo *pKeyInfo; /* Collating sequence for the result set */ + Select *pLoop; /* For looping through SELECT statements */ + CollSeq **apColl; + CollSeq **aCopy; + + assert( p->pRightmost==p ); + pKeyInfo = sqliteMalloc(sizeof(*pKeyInfo)+nCol*2*sizeof(CollSeq*) + nCol); + if( !pKeyInfo ){ + rc = SQLITE_NOMEM; + goto multi_select_end; + } + + pKeyInfo->enc = pParse->db->enc; + 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->addrOpenVirt[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->addrOpenVirt[1]<0 ); + break; + } + sqlite3VdbeChangeP2(v, addr, nCol); + sqlite3VdbeChangeP3(v, addr, (char*)pKeyInfo, P3_KEYINFO); + } + } + + if( pOrderBy ){ + struct ExprList_item *pOTerm = pOrderBy->a; + int nExpr = pOrderBy->nExpr; + int addr; + u8 *pSortOrder; + + aCopy = (CollSeq**)&pKeyInfo[1]; + pSortOrder = pKeyInfo->aSortOrder = (u8*)&aCopy[nExpr]; + memcpy(aCopy, pKeyInfo->aColl, nCol*sizeof(CollSeq*)); + apColl = pKeyInfo->aColl; + for(i=0; i<pOrderBy->nExpr; 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->addrOpenVirt[2]>=0 ); + addr = p->addrOpenVirt[2]; + sqlite3VdbeChangeP2(v, addr, p->pEList->nExpr+2); + pKeyInfo->nField = pOrderBy->nExpr; + 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->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) +** +** In this routine, the "p" parameter is a pointer to the outer query. +** The subquery is p->pSrc->a[iFrom]. isAgg is true if the outer query +** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates. +** +** If flattening is not attempted, this routine is a no-op and returns 0. +** If flattening is attempted this routine returns 1. +** +** All of the expression analysis must occur on both the outer query and +** the subquery before this routine runs. +*/ +static int flattenSubquery( + Parse *pParse, /* The parsing context */ + Select *p, /* The parent or outer SELECT statement */ + int iFrom, /* Index in p->pSrc->a[] of the inner subquery */ + int isAgg, /* True if outer SELECT uses aggregate functions */ + int subqueryIsAgg /* True if the subquery uses aggregate functions */ +){ + 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; + if( subqueryIsAgg && pSrc->nSrc>1 ) return 0; + pSubSrc = pSub->pSrc; + assert( pSubSrc ); + if( (pSub->pLimit && p->pLimit) || pSub->pOffset || + (pSub->pLimit && isAgg) ) return 0; + if( pSubSrc->nSrc==0 ) return 0; + if( pSub->isDistinct && (pSrc->nSrc>1 || isAgg) ){ + return 0; + } + if( p->isDistinct && subqueryIsAgg ) return 0; + if( (p->disallowOrderBy || p->pOrderBy) && pSub->pOrderBy ) return 0; + + /* 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". + */ + substExprList(p->pEList, iParent, pSub->pEList); + 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(pExpr->span.z, pExpr->span.n); + } + } + 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; + */ + 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; + int cont; + ExprList *pEList, *pList, eList; + struct ExprList_item eListItem; + SrcList *pSrc; + + /* 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(pExpr->token.z,"min",3)==0 ){ + seekOp = OP_Rewind; + }else if( sqlite3StrNICmp(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); + for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ + assert( pIdx->nColumn>=1 ); + if( pIdx->aiColumn[0]==iCol && pIdx->keyInfo.aColl[0]==pColl ) 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_VirtualTab ){ + sqlite3VdbeAddOp(v, OP_OpenVirtual, 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. + */ + sqlite3CodeVerifySchema(pParse, pTab->iDb); + base = pSrc->a[0].iCursor; + computeLimitRegisters(pParse, p); + if( pSrc->a[0].pSelect==0 ){ + sqlite3OpenTableForReading(v, base, pTab); + } + cont = sqlite3VdbeMakeLabel(v); + 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; + iIdx = pParse->nTab++; + sqlite3VdbeAddOp(v, OP_Integer, pIdx->iDb, 0); + sqlite3VdbeOp3(v, OP_OpenRead, iIdx, pIdx->tnum, + (char*)&pIdx->keyInfo, P3_KEYINFO); + 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, cont, cont, 0); + sqlite3VdbeResolveLabel(v, cont); + 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; + } + if( sqlite3ExprIsConstant(pE) ){ + sqlite3ErrorMsg(pParse, + "%s BY terms must not be non-integer constants", zType); + 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. + */ + sNC.pParse = pParse; + sNC.hasAgg = 0; + sNC.nErr = 0; + sNC.nRef = 0; + sNC.pEList = 0; + sNC.allowAgg = 0; + sNC.pSrcList = 0; + sNC.pNext = 0; + 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_OpenVirtual, 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, 2); + } + if( pF->pFunc->needCollSeq ){ + CollSeq *pColl = 0; + struct ExprList_item *pItem; + int j; + for(j=0, pItem=pList->a; !pColl && j<pList->nExpr; 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_OpenVirtual instruction */ + AggInfo sAggInfo; /* Information used by aggregate queries */ + + if( sqlite3_malloc_failed || pParse->nErr || p==0 ) 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. + */ + assert( eDest!=SRT_Exists || pEList->nExpr==1 ); +#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; + + /* 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( eDest==SRT_Callback ){ + generateColumnNames(pParse, pTabList, pEList); + } + + /* 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 ) continue; + if( pItem->zName!=0 ){ + zSavedAuthContext = pParse->zAuthContext; + pParse->zAuthContext = pItem->zName; + needRestoreContext = 1; + }else{ + needRestoreContext = 0; + } + sqlite3Select(pParse, pItem->pSelect, SRT_VirtualTab, + 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(pParse, 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_OpenVirtual 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->addrOpenVirt[2] = addrSortIndex = + sqlite3VdbeOp3(v, OP_OpenVirtual, pOrderBy->iECursor, pOrderBy->nExpr+2, + (char*)pKeyInfo, P3_KEYINFO_HANDOFF); + }else{ + addrSortIndex = -1; + } + + /* Set the limiter. + */ + computeLimitRegisters(pParse, p); + + /* If the output is destined for a temporary table, open that table. + */ + if( eDest==SRT_VirtualTab ){ + sqlite3VdbeAddOp(v, OP_OpenVirtual, iParm, pEList->nExpr); + } + + + /* Initialize the memory cell to NULL for SRT_Mem or 0 for SRT_Exists + */ + if( eDest==SRT_Mem ){ + sqlite3VdbeAddOp(v, OP_MemNull, iParm, 0); + }else if( eDest==SRT_Exists ){ + sqlite3VdbeAddOp(v, OP_MemInt, 0, iParm); + } + + /* 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_OpenVirtual, 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_OpenVirtual + ** instruction ended up not being needed, then change the OP_OpenVirtual + ** into an OP_Noop. + */ + if( addrSortIndex>=0 && pOrderBy==0 ){ + uncreateSortingIndex(pParse, addrSortIndex); + p->addrOpenVirt[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_OpenVirtual 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( sqlite3_malloc_failed ) 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 OpenVirtual instruction + ** will be converted into a Noop. + */ + sAggInfo.sortingIdx = pParse->nTab++; + pKeyInfo = keyInfoFromExprList(pParse, pGroupBy); + addrSortingIdx = + sqlite3VdbeOp3(v, OP_OpenVirtual, 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_OpenVirtual 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); + uncreateSortingIndex(pParse, addrSortingIdx); + } + + /* 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 delete the subquery structure from the parent + ** to prevent this subquery from being evaluated again and to force the + ** the use of the temporary table. + */ + if( pParent ){ + assert( pParent->pSrc->nSrc>parentTab ); + assert( pParent->pSrc->a[parentTab].pSelect==p ); + sqlite3SelectDelete(p); + pParent->pSrc->a[parentTab].pSelect = 0; + } +#endif + + /* 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: + sqliteFree(sAggInfo.aCol); + sqliteFree(sAggInfo.aFunc); + return rc; +} |