/* ** 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; jn==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; inCol; 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; inSrc-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; jnCol; 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; jnId; 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; inExpr; 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; ipExpr); 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; ipSrcList==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;jnSrc && pTabList->a[j].iCursor!=pExpr->iTable;j++); if( jnSrc ){ 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 && iColnCol) ); 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; inExpr; 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; inExpr; 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; jnSrc && pTabList->a[j].iCursor!=p->iTable; j++){} assert( jnSrc ); pTab = pTabList->a[j].pTab; if( iCol<0 ) iCol = pTab->iPKey; assert( iCol==-1 || (iCol>=0 && iColnCol) ); 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; inCol; 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 " phrase, use 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; jzName = 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; inSrc; 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; knExpr; 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( knExpr ){ /* ** 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; knExpr; 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; inSrc; 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; jnCol; 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; inExpr; 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; inExpr; 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 && jnExpr; 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( nSetP2pOrderBy; 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( nSetP2addrOpenVirt[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; idb->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; inExpr; i++, pOTerm++, apColl++, pSortOrder++){ Expr *pExpr = pOTerm->pExpr; char *zName = pOTerm->zName; assert( pExpr->op==TK_COLUMN && pExpr->iColumniColumn]; } *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->iColumnnExpr ); 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; inExpr; 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 && iFromnSrc ); 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; ipSrc = pSrc; for(i=pSrc->nSrc-1; i-extra>=iFrom; i--){ pSrc->a[i] = pSrc->a[i-extra]; } } for(i=0; ia[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; inExpr; 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; inExpr; 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; inExpr; 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; inExpr; 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; inColumn; i++){ sqlite3VdbeAddOp(v, OP_MemNull, pAggInfo->aCol[i].iMem, 0); } for(pFunc=pAggInfo->aFunc, i=0; inFunc; 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; inFunc; 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; inFunc; 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 && jnExpr; 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; inAccumulator; 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; inSrc; 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; inExpr; 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; ipList) ){ 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; iiSorterColumniColumn<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; jnExpr; 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, jnExpr-1); } for(j=pGroupBy->nExpr-1; j>=0; j--){ if( jnExpr-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; jnExpr; 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; }