/* ** 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 410099 2005-05-06 17:52:07Z staniek $ */ #include "sqliteInt.h" /* ** Allocate a new Select structure and return a pointer to that ** structure. */ Select *sqliteSelectNew( 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 */ int nLimit, /* LIMIT value. -1 means not used */ int nOffset /* OFFSET value. 0 means no offset */ ){ Select *pNew; pNew = sqliteMalloc( sizeof(*pNew) ); if( pNew==0 ){ sqliteExprListDelete(pEList); sqliteSrcListDelete(pSrc); sqliteExprDelete(pWhere); sqliteExprListDelete(pGroupBy); sqliteExprDelete(pHaving); sqliteExprListDelete(pOrderBy); }else{ if( pEList==0 ){ pEList = sqliteExprListAppend(0, sqliteExpr(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->nLimit = nLimit; pNew->nOffset = nOffset; pNew->iLimit = -1; pNew->iOffset = -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_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 sqliteJoinType(Parse *pParse, Token *pA, Token *pB, Token *pC){ int jointype = 0; Token *apAll[3]; Token *p; static struct { const char *zKeyword; int nChar; int 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 }, }; 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 && sqliteStrNICmp(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 ){ static Token dummy = { 0, 0 }; char *zSp1 = " ", *zSp2 = " "; if( pB==0 ){ pB = &dummy; zSp1 = 0; } if( pC==0 ){ pC = &dummy; zSp2 = 0; } sqliteSetNString(&pParse->zErrMsg, "unknown or unsupported join type: ", 0, pA->z, pA->n, zSp1, 1, pB->z, pB->n, zSp2, 1, pC->z, pC->n, 0); pParse->nErr++; jointype = JT_INNER; }else if( jointype & JT_RIGHT ){ sqliteErrorMsg(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( sqliteStrICmp(pTab->aCol[i].zName, zCol)==0 ) return i; } return -1; } /* ** 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 Table *pTab2, /* Second table */ Expr **ppExpr /* Add the equality term to this expression */ ){ Token dummy; Expr *pE1a, *pE1b, *pE1c; Expr *pE2a, *pE2b, *pE2c; Expr *pE; dummy.z = zCol; dummy.n = strlen(zCol); dummy.dyn = 0; pE1a = sqliteExpr(TK_ID, 0, 0, &dummy); pE2a = sqliteExpr(TK_ID, 0, 0, &dummy); dummy.z = pTab1->zName; dummy.n = strlen(dummy.z); pE1b = sqliteExpr(TK_ID, 0, 0, &dummy); dummy.z = pTab2->zName; dummy.n = strlen(dummy.z); pE2b = sqliteExpr(TK_ID, 0, 0, &dummy); pE1c = sqliteExpr(TK_DOT, pE1b, pE1a, 0); pE2c = sqliteExpr(TK_DOT, pE2b, pE2a, 0); pE = sqliteExpr(TK_EQ, pE1c, pE2c, 0); ExprSetProperty(pE, EP_FromJoin); if( *ppExpr ){ *ppExpr = sqliteExpr(TK_AND, *ppExpr, pE, 0); }else{ *ppExpr = pE; } } /* ** Set the EP_FromJoin property on all terms of the given 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. */ static void setJoinExpr(Expr *p){ while( p ){ ExprSetProperty(p, EP_FromJoin); setJoinExpr(p->pLeft); 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. ** ** This routine returns the number of errors encountered. */ static int sqliteProcessJoin(Parse *pParse, Select *p){ SrcList *pSrc; int i, j; pSrc = p->pSrc; for(i=0; inSrc-1; i++){ struct SrcList_item *pTerm = &pSrc->a[i]; struct SrcList_item *pOther = &pSrc->a[i+1]; if( pTerm->pTab==0 || pOther->pTab==0 ) continue; /* When the NATURAL keyword is present, add WHERE clause terms for ** every column that the two tables have in common. */ if( pTerm->jointype & JT_NATURAL ){ Table *pTab; if( pTerm->pOn || pTerm->pUsing ){ sqliteErrorMsg(pParse, "a NATURAL join may not have " "an ON or USING clause", 0); return 1; } pTab = pTerm->pTab; for(j=0; jnCol; j++){ if( columnIndex(pOther->pTab, pTab->aCol[j].zName)>=0 ){ addWhereTerm(pTab->aCol[j].zName, pTab, pOther->pTab, &p->pWhere); } } } /* Disallow both ON and USING clauses in the same join */ if( pTerm->pOn && pTerm->pUsing ){ sqliteErrorMsg(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 ** and AND operator. */ if( pTerm->pOn ){ setJoinExpr(pTerm->pOn); if( p->pWhere==0 ){ p->pWhere = pTerm->pOn; }else{ p->pWhere = sqliteExpr(TK_AND, p->pWhere, pTerm->pOn, 0); } pTerm->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( pTerm->pUsing ){ IdList *pList; int j; assert( inSrc-1 ); pList = pTerm->pUsing; for(j=0; jnId; j++){ if( columnIndex(pTerm->pTab, pList->a[j].zName)<0 || columnIndex(pOther->pTab, pList->a[j].zName)<0 ){ sqliteErrorMsg(pParse, "cannot join using column %s - column " "not present in both tables", pList->a[j].zName); return 1; } addWhereTerm(pList->a[j].zName, pTerm->pTab, pOther->pTab, &p->pWhere); } } } return 0; } /* ** Delete the given Select structure and all of its substructures. */ void sqliteSelectDelete(Select *p){ if( p==0 ) return; sqliteExprListDelete(p->pEList); sqliteSrcListDelete(p->pSrc); sqliteExprDelete(p->pWhere); sqliteExprListDelete(p->pGroupBy); sqliteExprDelete(p->pHaving); sqliteExprListDelete(p->pOrderBy); sqliteSelectDelete(p->pPrior); sqliteFree(p->zSelect); sqliteFree(p); } /* ** Delete the aggregate information from the parse structure. */ static void sqliteAggregateInfoReset(Parse *pParse){ sqliteFree(pParse->aAgg); pParse->aAgg = 0; pParse->nAgg = 0; pParse->useAgg = 0; } /* ** 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){ char *zSortOrder; int i; zSortOrder = sqliteMalloc( pOrderBy->nExpr + 1 ); if( zSortOrder==0 ) return; for(i=0; inExpr; i++){ int order = pOrderBy->a[i].sortOrder; int type; int c; if( (order & SQLITE_SO_TYPEMASK)==SQLITE_SO_TEXT ){ type = SQLITE_SO_TEXT; }else if( (order & SQLITE_SO_TYPEMASK)==SQLITE_SO_NUM ){ type = SQLITE_SO_NUM; }else if( pParse->db->file_format>=4 ){ type = sqliteExprType(pOrderBy->a[i].pExpr); }else{ type = SQLITE_SO_NUM; } if( (order & SQLITE_SO_DIRMASK)==SQLITE_SO_ASC ){ c = type==SQLITE_SO_TEXT ? 'A' : '+'; }else{ c = type==SQLITE_SO_TEXT ? 'D' : '-'; } zSortOrder[i] = c; sqliteExprCode(pParse, pOrderBy->a[i].pExpr); } zSortOrder[pOrderBy->nExpr] = 0; sqliteVdbeOp3(v, OP_SortMakeKey, pOrderBy->nExpr, 0, zSortOrder, P3_DYNAMIC); sqliteVdbeAddOp(v, OP_SortPut, 0, 0); } /* ** This routine adds a P3 argument to the last VDBE opcode that was ** inserted. The P3 argument added is a string suitable for the ** OP_MakeKey or OP_MakeIdxKey opcodes. The string consists of ** characters 't' or 'n' depending on whether or not the various ** fields of the key to be generated should be treated as numeric ** or as text. See the OP_MakeKey and OP_MakeIdxKey opcode ** documentation for additional information about the P3 string. ** See also the sqliteAddIdxKeyType() routine. */ void sqliteAddKeyType(Vdbe *v, ExprList *pEList){ int nColumn = pEList->nExpr; char *zType = sqliteMalloc( nColumn+1 ); int i; if( zType==0 ) return; for(i=0; ia[i].pExpr)==SQLITE_SO_NUM ? 'n' : 't'; } zType[i] = 0; sqliteVdbeChangeP3(v, -1, zType, P3_DYNAMIC); } /* ** 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 ){ int addr = sqliteVdbeCurrentAddr(v) + 2; if( nPop>0 ) addr++; sqliteVdbeAddOp(v, OP_MemIncr, p->iOffset, addr); if( nPop>0 ){ sqliteVdbeAddOp(v, OP_Pop, nPop, 0); } sqliteVdbeAddOp(v, OP_Goto, 0, iContinue); } if( p->iLimit>=0 ){ sqliteVdbeAddOp(v, OP_MemIncr, p->iLimit, iBreak); } } /* ** 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 */ ){ 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; for(i=0; inExpr; i++){ sqliteExprCode(pParse, pEList->a[i].pExpr); } } /* 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 ){ #if NULL_ALWAYS_DISTINCT sqliteVdbeAddOp(v, OP_IsNull, -pEList->nExpr, sqliteVdbeCurrentAddr(v)+7); #endif sqliteVdbeAddOp(v, OP_MakeKey, pEList->nExpr, 1); if( pParse->db->file_format>=4 ) sqliteAddKeyType(v, pEList); sqliteVdbeAddOp(v, OP_Distinct, distinct, sqliteVdbeCurrentAddr(v)+3); sqliteVdbeAddOp(v, OP_Pop, pEList->nExpr+1, 0); sqliteVdbeAddOp(v, OP_Goto, 0, iContinue); sqliteVdbeAddOp(v, OP_String, 0, 0); sqliteVdbeAddOp(v, OP_PutStrKey, distinct, 0); 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. */ case SRT_Union: { sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, NULL_ALWAYS_DISTINCT); sqliteVdbeAddOp(v, OP_String, 0, 0); sqliteVdbeAddOp(v, OP_PutStrKey, iParm, 0); break; } /* Store the result as data using a unique key. */ case SRT_Table: case SRT_TempTable: { sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, 0); if( pOrderBy ){ pushOntoSorter(pParse, v, pOrderBy); }else{ sqliteVdbeAddOp(v, OP_NewRecno, iParm, 0); sqliteVdbeAddOp(v, OP_Pull, 1, 0); sqliteVdbeAddOp(v, OP_PutIntKey, 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 = sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, NULL_ALWAYS_DISTINCT); sqliteVdbeAddOp(v, OP_NotFound, iParm, addr+3); sqliteVdbeAddOp(v, OP_Delete, iParm, 0); break; } /* 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 = sqliteVdbeCurrentAddr(v); int addr2; assert( nColumn==1 ); sqliteVdbeAddOp(v, OP_NotNull, -1, addr1+3); sqliteVdbeAddOp(v, OP_Pop, 1, 0); addr2 = sqliteVdbeAddOp(v, OP_Goto, 0, 0); if( pOrderBy ){ pushOntoSorter(pParse, v, pOrderBy); }else{ sqliteVdbeAddOp(v, OP_String, 0, 0); sqliteVdbeAddOp(v, OP_PutStrKey, iParm, 0); } sqliteVdbeChangeP2(v, addr2, sqliteVdbeCurrentAddr(v)); break; } /* If this is a scalar select that is part of an expression, then ** store the results in the appropriate memory cell and break out ** of the scan loop. */ case SRT_Mem: { assert( nColumn==1 ); if( pOrderBy ){ pushOntoSorter(pParse, v, pOrderBy); }else{ sqliteVdbeAddOp(v, OP_MemStore, iParm, 1); sqliteVdbeAddOp(v, OP_Goto, 0, iBreak); } break; } /* Send the data to the callback function. */ case SRT_Callback: case SRT_Sorter: { if( pOrderBy ){ sqliteVdbeAddOp(v, OP_SortMakeRec, nColumn, 0); pushOntoSorter(pParse, v, pOrderBy); }else{ assert( eDest==SRT_Callback ); sqliteVdbeAddOp(v, OP_Callback, nColumn, 0); } break; } /* Invoke a subroutine to handle the results. The subroutine itself ** is responsible for popping the results off of the stack. */ case SRT_Subroutine: { if( pOrderBy ){ sqliteVdbeAddOp(v, OP_MakeRecord, nColumn, 0); pushOntoSorter(pParse, v, pOrderBy); }else{ sqliteVdbeAddOp(v, OP_Gosub, 0, iParm); } break; } /* 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 ); sqliteVdbeAddOp(v, OP_Pop, nColumn, 0); break; } } return 0; } /* ** 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( 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 end1 = sqliteVdbeMakeLabel(v); int end2 = sqliteVdbeMakeLabel(v); int addr; if( eDest==SRT_Sorter ) return; sqliteVdbeAddOp(v, OP_Sort, 0, 0); addr = sqliteVdbeAddOp(v, OP_SortNext, 0, end1); codeLimiter(v, p, addr, end2, 1); switch( eDest ){ case SRT_Callback: { sqliteVdbeAddOp(v, OP_SortCallback, nColumn, 0); break; } case SRT_Table: case SRT_TempTable: { sqliteVdbeAddOp(v, OP_NewRecno, iParm, 0); sqliteVdbeAddOp(v, OP_Pull, 1, 0); sqliteVdbeAddOp(v, OP_PutIntKey, iParm, 0); break; } case SRT_Set: { assert( nColumn==1 ); sqliteVdbeAddOp(v, OP_NotNull, -1, sqliteVdbeCurrentAddr(v)+3); sqliteVdbeAddOp(v, OP_Pop, 1, 0); sqliteVdbeAddOp(v, OP_Goto, 0, sqliteVdbeCurrentAddr(v)+3); sqliteVdbeAddOp(v, OP_String, 0, 0); sqliteVdbeAddOp(v, OP_PutStrKey, iParm, 0); break; } case SRT_Mem: { assert( nColumn==1 ); sqliteVdbeAddOp(v, OP_MemStore, iParm, 1); sqliteVdbeAddOp(v, OP_Goto, 0, end1); break; } case SRT_Subroutine: { int i; for(i=0; ipVdbe; int i, j; for(i=0; inExpr; i++){ Expr *p = pEList->a[i].pExpr; char *zType = 0; if( p==0 ) continue; if( p->op==TK_COLUMN && pTabList ){ Table *pTab; 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 ){ zType = "INTEGER"; }else{ zType = pTab->aCol[iCol].zType; } }else{ if( sqliteExprType(p)==SQLITE_SO_TEXT ){ zType = "TEXT"; }else{ zType = "NUMERIC"; } } sqliteVdbeOp3(v, OP_ColumnName, i + pEList->nExpr, 0, zType, 0); } } /* ** 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; sqlite *db = pParse->db; int fullNames, shortNames; assert( v!=0 ); if( pParse->colNamesSet || v==0 || sqlite_malloc_failed ) return; pParse->colNamesSet = 1; fullNames = (db->flags & SQLITE_FullColNames)!=0; shortNames = (db->flags & SQLITE_ShortColNames)!=0; for(i=0; inExpr; i++){ Expr *p; int p2 = i==pEList->nExpr-1; p = pEList->a[i].pExpr; if( p==0 ) continue; if( pEList->a[i].zName ){ char *zName = pEList->a[i].zName; sqliteVdbeOp3(v, OP_ColumnName, i, p2, zName, 0); 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] ){ int addr = sqliteVdbeOp3(v,OP_ColumnName, i, p2, p->span.z, p->span.n); sqliteVdbeCompressSpace(v, addr); }else if( fullNames || (!shortNames && pTabList->nSrc>1) ){ char *zName = 0; char *zTab; zTab = pTabList->a[j].zAlias; if( fullNames || zTab==0 ) zTab = pTab->zName; sqliteSetString(&zName, zTab, ".", zCol, 0); sqliteVdbeOp3(v, OP_ColumnName, i, p2, zName, P3_DYNAMIC); }else{ sqliteVdbeOp3(v, OP_ColumnName, i, p2, zCol, 0); } }else if( p->span.z && p->span.z[0] ){ int addr = sqliteVdbeOp3(v,OP_ColumnName, i, p2, p->span.z, p->span.n); sqliteVdbeCompressSpace(v, addr); }else{ char zName[30]; assert( p->op!=TK_COLUMN || pTabList==0 ); sprintf(zName, "column%d", i+1); sqliteVdbeOp3(v, OP_ColumnName, i, p2, zName, 0); } } } /* ** 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; } /* ** Forward declaration */ static int fillInColumnList(Parse*, Select*); /* ** Given a SELECT statement, generate a Table structure that describes ** the result set of that SELECT. */ Table *sqliteResultSetOfSelect(Parse *pParse, char *zTabName, Select *pSelect){ Table *pTab; int i, j; ExprList *pEList; Column *aCol; if( fillInColumnList(pParse, pSelect) ){ return 0; } pTab = sqliteMalloc( sizeof(Table) ); if( pTab==0 ){ return 0; } 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; inCol; i++){ Expr *p, *pR; if( pEList->a[i].zName ){ aCol[i].zName = sqliteStrDup(pEList->a[i].zName); }else if( (p=pEList->a[i].pExpr)->op==TK_DOT && (pR=p->pRight)!=0 && pR->token.z && pR->token.z[0] ){ int cnt; sqliteSetNString(&aCol[i].zName, pR->token.z, pR->token.n, 0); for(j=cnt=0; jtoken.z, pR->token.n, zBuf, n,0); j = -1; } } }else if( p->span.z && p->span.z[0] ){ sqliteSetNString(&pTab->aCol[i].zName, p->span.z, p->span.n, 0); }else{ char zBuf[30]; sprintf(zBuf, "column%d", i+1); aCol[i].zName = sqliteStrDup(zBuf); } sqliteDequote(aCol[i].zName); } pTab->iPKey = -1; return pTab; } /* ** For the given SELECT statement, do three things. ** ** (1) Fill in the pTabList->a[].pTab fields in the SrcList that ** defines the set of tables that should be scanned. For views, ** 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. ** ** (2) Add terms to the WHERE clause to accomodate the NATURAL keyword ** on joins and the ON and USING clause of joins. ** ** (3) 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 fillInColumnList(Parse *pParse, Select *p){ int i, j, k, rc; SrcList *pTabList; ExprList *pEList; Table *pTab; if( p==0 || p->pSrc==0 ) return 1; pTabList = p->pSrc; pEList = p->pEList; /* Look up every table in the table list. */ for(i=0; inSrc; i++){ if( pTabList->a[i].pTab ){ /* This routine has run before! No need to continue */ return 0; } if( pTabList->a[i].zName==0 ){ /* A sub-query in the FROM clause of a SELECT */ assert( pTabList->a[i].pSelect!=0 ); if( pTabList->a[i].zAlias==0 ){ char zFakeName[60]; sprintf(zFakeName, "sqlite_subquery_%p_", (void*)pTabList->a[i].pSelect); sqliteSetString(&pTabList->a[i].zAlias, zFakeName, 0); } pTabList->a[i].pTab = pTab = sqliteResultSetOfSelect(pParse, pTabList->a[i].zAlias, pTabList->a[i].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; }else{ /* An ordinary table or view name in the FROM clause */ pTabList->a[i].pTab = pTab = sqliteLocateTable(pParse,pTabList->a[i].zName,pTabList->a[i].zDatabase); if( pTab==0 ){ return 1; } if( pTab->pSelect ){ /* We reach here if the named table is a really a view */ if( sqliteViewGetColumnNames(pParse, pTab) ){ return 1; } /* If pTabList->a[i].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( pTabList->a[i].pSelect==0 ){ pTabList->a[i].pSelect = sqliteSelectDup(pTab->pSelect); } } } } /* 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; 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 = sqliteExprListAppend(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 = sqliteTableNameFromToken(&pE->pLeft->token); }else{ zTName = 0; } for(i=0; inSrc; i++){ Table *pTab = pTabList->a[i].pTab; char *zTabName = pTabList->a[i].zAlias; if( zTabName==0 || zTabName[0]==0 ){ zTabName = pTab->zName; } if( zTName && (zTabName==0 || zTabName[0]==0 || sqliteStrICmp(zTName, zTabName)!=0) ){ continue; } tableSeen = 1; for(j=0; jnCol; j++){ Expr *pExpr, *pLeft, *pRight; char *zName = pTab->aCol[j].zName; if( i>0 && (pTabList->a[i-1].jointype & JT_NATURAL)!=0 && columnIndex(pTabList->a[i-1].pTab, zName)>=0 ){ /* In a NATURAL join, omit the join columns from the ** table on the right */ continue; } if( i>0 && sqliteIdListIndex(pTabList->a[i-1].pUsing, zName)>=0 ){ /* In a join with a USING clause, omit columns in the ** using clause from the table on the right. */ continue; } pRight = sqliteExpr(TK_ID, 0, 0, 0); if( pRight==0 ) break; pRight->token.z = zName; pRight->token.n = strlen(zName); pRight->token.dyn = 0; if( zTabName && pTabList->nSrc>1 ){ pLeft = sqliteExpr(TK_ID, 0, 0, 0); pExpr = sqliteExpr(TK_DOT, pLeft, pRight, 0); if( pExpr==0 ) break; pLeft->token.z = zTabName; pLeft->token.n = strlen(zTabName); pLeft->token.dyn = 0; sqliteSetString((char**)&pExpr->span.z, zTabName, ".", zName, 0); pExpr->span.n = strlen(pExpr->span.z); pExpr->span.dyn = 1; pExpr->token.z = 0; pExpr->token.n = 0; pExpr->token.dyn = 0; }else{ pExpr = pRight; pExpr->span = pExpr->token; } pNew = sqliteExprListAppend(pNew, pExpr, 0); } } if( !tableSeen ){ if( zTName ){ sqliteErrorMsg(pParse, "no such table: %s", zTName); }else{ sqliteErrorMsg(pParse, "no tables specified"); } rc = 1; } sqliteFree(zTName); } } sqliteExprListDelete(pEList); p->pEList = pNew; } return rc; } /* ** This routine recursively unlinks the Select.pSrc.a[].pTab pointers ** in a select structure. It just sets the pointers to NULL. This ** routine is recursive in the sense that if the Select.pSrc.a[].pSelect ** pointer is not NULL, this routine is called recursively on that pointer. ** ** This routine is called on the Select structure that defines a ** VIEW in order to undo any bindings to tables. This is necessary ** because those tables might be DROPed by a subsequent SQL command. ** If the bindings are not removed, then the Select.pSrc->a[].pTab field ** will be left pointing to a deallocated Table structure after the ** DROP and a coredump will occur the next time the VIEW is used. */ void sqliteSelectUnbind(Select *p){ int i; SrcList *pSrc = p->pSrc; Table *pTab; if( p==0 ) return; for(i=0; inSrc; i++){ if( (pTab = pSrc->a[i].pTab)!=0 ){ if( pTab->isTransient ){ sqliteDeleteTable(0, pTab); } pSrc->a[i].pTab = 0; if( pSrc->a[i].pSelect ){ sqliteSelectUnbind(pSrc->a[i].pSelect); } } } } /* ** 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. ** ** This routine does NOT correctly initialize the Expr.dataType field ** of the ORDER BY expressions. The multiSelectSortOrder() routine ** must be called to do that after the individual select statements ** have all been analyzed. This routine is unable to compute Expr.dataType ** because it must be called before the individual select statements ** have been analyzed. */ 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( fillInColumnList(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( sqliteExprIsInteger(pE, &iCol) ){ if( iCol<=0 || iCol>pEList->nExpr ){ sqliteErrorMsg(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; assert( pE->token.z ); zLabel = sqliteStrNDup(pE->token.z, pE->token.n); sqliteDequote(zLabel); if( sqliteStrICmp(zName, zLabel)==0 ){ iCol = j; } sqliteFree(zLabel); } if( iCol<0 && sqliteExprCompare(pE, pEList->a[j].pExpr) ){ iCol = j; } } if( iCol>=0 ){ pE->op = TK_COLUMN; pE->iColumn = iCol; pE->iTable = iTable; pOrderBy->a[i].done = 1; } if( iCol<0 && mustComplete ){ sqliteErrorMsg(pParse, "ORDER BY term number %d does not match any result column", i+1); nErr++; break; } } return nErr; } /* ** 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 *sqliteGetVdbe(Parse *pParse){ Vdbe *v = pParse->pVdbe; if( v==0 ){ v = pParse->pVdbe = sqliteVdbeCreate(pParse->db); } return v; } /* ** This routine sets the Expr.dataType field on all elements of ** the pOrderBy expression list. The pOrderBy list will have been ** set up by matchOrderbyToColumn(). Hence each expression has ** a TK_COLUMN as its root node. The Expr.iColumn refers to a ** column in the result set. The datatype is set to SQLITE_SO_TEXT ** if the corresponding column in p and every SELECT to the left of ** p has a datatype of SQLITE_SO_TEXT. If the cooressponding column ** in p or any of the left SELECTs is SQLITE_SO_NUM, then the datatype ** of the order-by expression is set to SQLITE_SO_NUM. ** ** Examples: ** ** CREATE TABLE one(a INTEGER, b TEXT); ** CREATE TABLE two(c VARCHAR(5), d FLOAT); ** ** SELECT b, b FROM one UNION SELECT d, c FROM two ORDER BY 1, 2; ** ** The primary sort key will use SQLITE_SO_NUM because the "d" in ** the second SELECT is numeric. The 1st column of the first SELECT ** is text but that does not matter because a numeric always overrides ** a text. ** ** The secondary key will use the SQLITE_SO_TEXT sort order because ** both the (second) "b" in the first SELECT and the "c" in the second ** SELECT have a datatype of text. */ static void multiSelectSortOrder(Select *p, ExprList *pOrderBy){ int i; ExprList *pEList; if( pOrderBy==0 ) return; if( p==0 ){ for(i=0; inExpr; i++){ pOrderBy->a[i].pExpr->dataType = SQLITE_SO_TEXT; } return; } multiSelectSortOrder(p->pPrior, pOrderBy); pEList = p->pEList; for(i=0; inExpr; i++){ Expr *pE = pOrderBy->a[i].pExpr; if( pE->dataType==SQLITE_SO_NUM ) continue; assert( pE->iColumn>=0 ); if( pEList->nExpr>pE->iColumn ){ pE->dataType = sqliteExprType(pEList->a[pE->iColumn].pExpr); } } } /* ** Compute the iLimit and iOffset fields of the SELECT based on the ** nLimit and nOffset fields. nLimit and nOffset hold the integers ** that appear in the original SQL statement after the LIMIT and OFFSET ** keywords. Or that hold -1 and 0 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){ /* ** If the comparison is p->nLimit>0 then "LIMIT 0" shows ** all rows. It is the same as no limit. If the comparision is ** p->nLimit>=0 then "LIMIT 0" show no rows at all. ** "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->nLimit>=0 ){ int iMem = pParse->nMem++; Vdbe *v = sqliteGetVdbe(pParse); if( v==0 ) return; sqliteVdbeAddOp(v, OP_Integer, -p->nLimit, 0); sqliteVdbeAddOp(v, OP_MemStore, iMem, 1); p->iLimit = iMem; } if( p->nOffset>0 ){ int iMem = pParse->nMem++; Vdbe *v = sqliteGetVdbe(pParse); if( v==0 ) return; sqliteVdbeAddOp(v, OP_Integer, -p->nOffset, 0); sqliteVdbeAddOp(v, OP_MemStore, iMem, 1); p->iOffset = iMem; } } /* ** 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, Select *p, int eDest, int iParm){ int rc; /* Success code from a subroutine */ Select *pPrior; /* Another SELECT immediately to our left */ Vdbe *v; /* Generate code to this VDBE */ /* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs. Only ** the last SELECT in the series may have an ORDER BY or LIMIT. */ if( p==0 || p->pPrior==0 ) return 1; pPrior = p->pPrior; if( pPrior->pOrderBy ){ sqliteErrorMsg(pParse,"ORDER BY clause should come after %s not before", selectOpName(p->op)); return 1; } if( pPrior->nLimit>=0 || pPrior->nOffset>0 ){ sqliteErrorMsg(pParse,"LIMIT clause should come after %s not before", selectOpName(p->op)); return 1; } /* Make sure we have a valid query engine. If not, create a new one. */ v = sqliteGetVdbe(pParse); if( v==0 ) return 1; /* Create the destination temporary table if necessary */ if( eDest==SRT_TempTable ){ sqliteVdbeAddOp(v, OP_OpenTemp, iParm, 0); eDest = SRT_Table; } /* Generate code for the left and right SELECT statements. */ switch( p->op ){ case TK_ALL: { if( p->pOrderBy==0 ){ pPrior->nLimit = p->nLimit; pPrior->nOffset = p->nOffset; rc = sqliteSelect(pParse, pPrior, eDest, iParm, 0, 0, 0); if( rc ) return rc; p->pPrior = 0; p->iLimit = pPrior->iLimit; p->iOffset = pPrior->iOffset; p->nLimit = -1; p->nOffset = 0; rc = sqliteSelect(pParse, p, eDest, iParm, 0, 0, 0); p->pPrior = pPrior; if( rc ) return rc; 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; /* One of the SRT_ operations to apply to self */ int priorOp; /* The SRT_ operation to apply to prior selects */ int nLimit, nOffset; /* Saved values of p->nLimit and p->nOffset */ ExprList *pOrderBy; /* The ORDER BY clause for the right SELECT */ priorOp = p->op==TK_ALL ? SRT_Table : SRT_Union; if( eDest==priorOp && p->pOrderBy==0 && p->nLimit<0 && p->nOffset==0 ){ /* 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( p->pOrderBy && matchOrderbyToColumn(pParse, p, p->pOrderBy, unionTab, 1) ){ return 1; } if( p->op!=TK_ALL ){ sqliteVdbeAddOp(v, OP_OpenTemp, unionTab, 1); sqliteVdbeAddOp(v, OP_KeyAsData, unionTab, 1); }else{ sqliteVdbeAddOp(v, OP_OpenTemp, unionTab, 0); } } /* Code the SELECT statements to our left */ rc = sqliteSelect(pParse, pPrior, priorOp, unionTab, 0, 0, 0); if( rc ) return rc; /* 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; pOrderBy = p->pOrderBy; p->pOrderBy = 0; nLimit = p->nLimit; p->nLimit = -1; nOffset = p->nOffset; p->nOffset = 0; rc = sqliteSelect(pParse, p, op, unionTab, 0, 0, 0); p->pPrior = pPrior; p->pOrderBy = pOrderBy; p->nLimit = nLimit; p->nOffset = nOffset; if( rc ) return rc; /* 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); generateColumnTypes(pParse, p->pSrc, p->pEList); } iBreak = sqliteVdbeMakeLabel(v); iCont = sqliteVdbeMakeLabel(v); sqliteVdbeAddOp(v, OP_Rewind, unionTab, iBreak); computeLimitRegisters(pParse, p); iStart = sqliteVdbeCurrentAddr(v); multiSelectSortOrder(p, p->pOrderBy); rc = selectInnerLoop(pParse, p, p->pEList, unionTab, p->pEList->nExpr, p->pOrderBy, -1, eDest, iParm, iCont, iBreak); if( rc ) return 1; sqliteVdbeResolveLabel(v, iCont); sqliteVdbeAddOp(v, OP_Next, unionTab, iStart); sqliteVdbeResolveLabel(v, iBreak); sqliteVdbeAddOp(v, OP_Close, unionTab, 0); if( p->pOrderBy ){ generateSortTail(p, v, p->pEList->nExpr, eDest, iParm); } } break; } case TK_INTERSECT: { int tab1, tab2; int iCont, iBreak, iStart; int nLimit, nOffset; /* 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( p->pOrderBy && matchOrderbyToColumn(pParse,p,p->pOrderBy,tab1,1) ){ return 1; } sqliteVdbeAddOp(v, OP_OpenTemp, tab1, 1); sqliteVdbeAddOp(v, OP_KeyAsData, tab1, 1); /* Code the SELECTs to our left into temporary table "tab1". */ rc = sqliteSelect(pParse, pPrior, SRT_Union, tab1, 0, 0, 0); if( rc ) return rc; /* Code the current SELECT into temporary table "tab2" */ sqliteVdbeAddOp(v, OP_OpenTemp, tab2, 1); sqliteVdbeAddOp(v, OP_KeyAsData, tab2, 1); p->pPrior = 0; nLimit = p->nLimit; p->nLimit = -1; nOffset = p->nOffset; p->nOffset = 0; rc = sqliteSelect(pParse, p, SRT_Union, tab2, 0, 0, 0); p->pPrior = pPrior; p->nLimit = nLimit; p->nOffset = nOffset; if( rc ) return rc; /* Generate code to take the intersection of the two temporary ** tables. */ assert( p->pEList ); if( eDest==SRT_Callback ){ generateColumnNames(pParse, 0, p->pEList); generateColumnTypes(pParse, p->pSrc, p->pEList); } iBreak = sqliteVdbeMakeLabel(v); iCont = sqliteVdbeMakeLabel(v); sqliteVdbeAddOp(v, OP_Rewind, tab1, iBreak); computeLimitRegisters(pParse, p); iStart = sqliteVdbeAddOp(v, OP_FullKey, tab1, 0); sqliteVdbeAddOp(v, OP_NotFound, tab2, iCont); multiSelectSortOrder(p, p->pOrderBy); rc = selectInnerLoop(pParse, p, p->pEList, tab1, p->pEList->nExpr, p->pOrderBy, -1, eDest, iParm, iCont, iBreak); if( rc ) return 1; sqliteVdbeResolveLabel(v, iCont); sqliteVdbeAddOp(v, OP_Next, tab1, iStart); sqliteVdbeResolveLabel(v, iBreak); sqliteVdbeAddOp(v, OP_Close, tab2, 0); sqliteVdbeAddOp(v, OP_Close, tab1, 0); if( p->pOrderBy ){ generateSortTail(p, v, p->pEList->nExpr, eDest, iParm); } break; } } assert( p->pEList && pPrior->pEList ); if( p->pEList->nExpr!=pPrior->pEList->nExpr ){ sqliteErrorMsg(pParse, "SELECTs to the left and right of %s" " do not have the same number of result columns", selectOpName(p->op)); return 1; } return 0; } /* ** 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 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; pExpr->dataType = pNew->dataType; assert( pExpr->pLeft==0 ); pExpr->pLeft = sqliteExprDup(pNew->pLeft); assert( pExpr->pRight==0 ); pExpr->pRight = sqliteExprDup(pNew->pRight); assert( pExpr->pList==0 ); pExpr->pList = sqliteExprListDup(pNew->pList); pExpr->iTable = pNew->iTable; pExpr->iColumn = pNew->iColumn; pExpr->iAgg = pNew->iAgg; sqliteTokenCopy(&pExpr->token, &pNew->token); sqliteTokenCopy(&pExpr->span, &pNew->span); } }else{ substExpr(pExpr->pLeft, iTable, pEList); substExpr(pExpr->pRight, 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); } } /* ** 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; Expr *pWhere; /* Check to see if flattening is permitted. Return 0 if not. */ if( p==0 ) return 0; pSrc = p->pSrc; assert( pSrc && iFrom>=0 && iFromnSrc ); pSub = pSrc->a[iFrom].pSelect; assert( pSub!=0 ); if( isAgg && subqueryIsAgg ) return 0; if( subqueryIsAgg && pSrc->nSrc>1 ) return 0; pSubSrc = pSub->pSrc; assert( pSubSrc ); if( pSubSrc->nSrc==0 ) return 0; if( (pSub->isDistinct || pSub->nLimit>=0) && (pSrc->nSrc>1 || isAgg) ){ return 0; } if( (p->isDistinct || p->nLimit>=0) && subqueryIsAgg ) return 0; if( 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 = pSrc->a[iFrom].iCursor; { int nSubSrc = pSubSrc->nSrc; int jointype = pSrc->a[iFrom].jointype; if( pSrc->a[iFrom].pTab && pSrc->a[iFrom].pTab->isTransient ){ sqliteDeleteTable(0, pSrc->a[iFrom].pTab); } sqliteFree(pSrc->a[iFrom].zDatabase); sqliteFree(pSrc->a[iFrom].zName); sqliteFree(pSrc->a[iFrom].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 = sqliteExprDup(pSub->pWhere); }else{ pWhere = 0; } if( subqueryIsAgg ){ assert( p->pHaving==0 ); p->pHaving = p->pWhere; p->pWhere = pWhere; substExpr(p->pHaving, iParent, pSub->pEList); if( pSub->pHaving ){ Expr *pHaving = sqliteExprDup(pSub->pHaving); if( p->pHaving ){ p->pHaving = sqliteExpr(TK_AND, p->pHaving, pHaving, 0); }else{ p->pHaving = pHaving; } } assert( p->pGroupBy==0 ); p->pGroupBy = sqliteExprListDup(pSub->pGroupBy); }else if( p->pWhere==0 ){ p->pWhere = pWhere; }else{ substExpr(p->pWhere, iParent, pSub->pEList); if( pWhere ){ p->pWhere = sqliteExpr(TK_AND, p->pWhere, pWhere, 0); } } /* The flattened query is distinct if either the inner or the ** outer query is distinct. */ p->isDistinct = p->isDistinct || pSub->isDistinct; /* Transfer the limit expression from the subquery to the outer ** query. */ if( pSub->nLimit>=0 ){ if( p->nLimit<0 ){ p->nLimit = pSub->nLimit; }else if( p->nLimit+p->nOffset > pSub->nLimit+pSub->nOffset ){ p->nLimit = pSub->nLimit + pSub->nOffset - p->nOffset; } } p->nOffset += pSub->nOffset; /* Finially, delete what is left of the subquery and return ** success. */ sqliteSelectDelete(pSub); return 1; } /* ** 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 sqliteSelect(). ** 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( sqliteStrNICmp(pExpr->token.z,"min",3)==0 ){ seekOp = OP_Rewind; }else if( sqliteStrNICmp(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{ for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ assert( pIdx->nColumn>=1 ); if( pIdx->aiColumn[0]==iCol ) 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 = sqliteGetVdbe(pParse); if( v==0 ) return 0; if( eDest==SRT_Callback ){ generateColumnTypes(pParse, p->pSrc, p->pEList); } /* If the output is destined for a temporary table, open that table. */ if( eDest==SRT_TempTable ){ sqliteVdbeAddOp(v, OP_OpenTemp, iParm, 0); } /* 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. */ sqliteCodeVerifySchema(pParse, pTab->iDb); base = pSrc->a[0].iCursor; computeLimitRegisters(pParse, p); if( pSrc->a[0].pSelect==0 ){ sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0); sqliteVdbeOp3(v, OP_OpenRead, base, pTab->tnum, pTab->zName, 0); } cont = sqliteVdbeMakeLabel(v); if( pIdx==0 ){ sqliteVdbeAddOp(v, seekOp, base, 0); }else{ sqliteVdbeAddOp(v, OP_Integer, pIdx->iDb, 0); sqliteVdbeOp3(v, OP_OpenRead, base+1, pIdx->tnum, pIdx->zName, P3_STATIC); if( seekOp==OP_Rewind ){ sqliteVdbeAddOp(v, OP_String, 0, 0); sqliteVdbeAddOp(v, OP_MakeKey, 1, 0); sqliteVdbeAddOp(v, OP_IncrKey, 0, 0); seekOp = OP_MoveTo; } sqliteVdbeAddOp(v, seekOp, base+1, 0); sqliteVdbeAddOp(v, OP_IdxRecno, base+1, 0); sqliteVdbeAddOp(v, OP_Close, base+1, 0); sqliteVdbeAddOp(v, OP_MoveTo, 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); sqliteVdbeResolveLabel(v, cont); sqliteVdbeAddOp(v, OP_Close, base, 0); return 1; } /* ** 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 a table with cursor 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 sqliteSelect( 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 */ ){ int i; WhereInfo *pWInfo; Vdbe *v; int isAgg = 0; /* 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 */ if( sqlite_malloc_failed || pParse->nErr || p==0 ) return 1; if( sqliteAuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1; /* If there is are a sequence of queries, do the earlier ones first. */ if( p->pPrior ){ return multiSelect(pParse, p, eDest, iParm); } /* Make local copies of the parameters for this query. */ pTabList = p->pSrc; pWhere = p->pWhere; pOrderBy = p->pOrderBy; pGroupBy = p->pGroupBy; pHaving = p->pHaving; isDistinct = p->isDistinct; /* Allocate VDBE cursors for each table in the FROM clause */ sqliteSrcListAssignCursors(pParse, pTabList); /* ** 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; /* Expand any "*" terms in the result set. (For example the "*" in ** "SELECT * FROM t1") The fillInColumnlist() routine also does some ** other housekeeping - see the header comment for details. */ if( fillInColumnList(pParse, p) ){ goto select_end; } pWhere = p->pWhere; pEList = p->pEList; if( pEList==0 ) goto select_end; /* If writing to memory or generating a set ** only a single column may be output. */ if( (eDest==SRT_Mem || eDest==SRT_Set) && pEList->nExpr>1 ){ sqliteErrorMsg(pParse, "only a single result allowed for " "a SELECT that is part of an expression"); goto select_end; } /* ORDER BY is ignored for some destinations. */ switch( eDest ){ case SRT_Union: case SRT_Except: case SRT_Discard: pOrderBy = 0; break; default: break; } /* At this point, we should have allocated all the cursors that we ** need to handle subquerys and temporary tables. ** ** Resolve the column names and do a semantics check on all the expressions. */ for(i=0; inExpr; i++){ if( sqliteExprResolveIds(pParse, pTabList, 0, pEList->a[i].pExpr) ){ goto select_end; } if( sqliteExprCheck(pParse, pEList->a[i].pExpr, 1, &isAgg) ){ goto select_end; } } if( pWhere ){ if( sqliteExprResolveIds(pParse, pTabList, pEList, pWhere) ){ goto select_end; } if( sqliteExprCheck(pParse, pWhere, 0, 0) ){ goto select_end; } } if( pHaving ){ if( pGroupBy==0 ){ sqliteErrorMsg(pParse, "a GROUP BY clause is required before HAVING"); goto select_end; } if( sqliteExprResolveIds(pParse, pTabList, pEList, pHaving) ){ goto select_end; } if( sqliteExprCheck(pParse, pHaving, 1, &isAgg) ){ goto select_end; } } if( pOrderBy ){ for(i=0; inExpr; i++){ int iCol; Expr *pE = pOrderBy->a[i].pExpr; if( sqliteExprIsInteger(pE, &iCol) && iCol>0 && iCol<=pEList->nExpr ){ sqliteExprDelete(pE); pE = pOrderBy->a[i].pExpr = sqliteExprDup(pEList->a[iCol-1].pExpr); } if( sqliteExprResolveIds(pParse, pTabList, pEList, pE) ){ goto select_end; } if( sqliteExprCheck(pParse, pE, isAgg, 0) ){ goto select_end; } if( sqliteExprIsConstant(pE) ){ if( sqliteExprIsInteger(pE, &iCol)==0 ){ sqliteErrorMsg(pParse, "ORDER BY terms must not be non-integer constants"); goto select_end; }else if( iCol<=0 || iCol>pEList->nExpr ){ sqliteErrorMsg(pParse, "ORDER BY column number %d out of range - should be " "between 1 and %d", iCol, pEList->nExpr); goto select_end; } } } } if( pGroupBy ){ for(i=0; inExpr; i++){ int iCol; Expr *pE = pGroupBy->a[i].pExpr; if( sqliteExprIsInteger(pE, &iCol) && iCol>0 && iCol<=pEList->nExpr ){ sqliteExprDelete(pE); pE = pGroupBy->a[i].pExpr = sqliteExprDup(pEList->a[iCol-1].pExpr); } if( sqliteExprResolveIds(pParse, pTabList, pEList, pE) ){ goto select_end; } if( sqliteExprCheck(pParse, pE, isAgg, 0) ){ goto select_end; } if( sqliteExprIsConstant(pE) ){ if( sqliteExprIsInteger(pE, &iCol)==0 ){ sqliteErrorMsg(pParse, "GROUP BY terms must not be non-integer constants"); goto select_end; }else if( iCol<=0 || iCol>pEList->nExpr ){ sqliteErrorMsg(pParse, "GROUP BY column number %d out of range - should be " "between 1 and %d", iCol, pEList->nExpr); goto select_end; } } } } /* Begin generating code. */ v = sqliteGetVdbe(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 */ for(i=0; inSrc; i++){ const char *zSavedAuthContext; int needRestoreContext; if( pTabList->a[i].pSelect==0 ) continue; if( pTabList->a[i].zName!=0 ){ zSavedAuthContext = pParse->zAuthContext; pParse->zAuthContext = pTabList->a[i].zName; needRestoreContext = 1; }else{ needRestoreContext = 0; } sqliteSelect(pParse, pTabList->a[i].pSelect, SRT_TempTable, pTabList->a[i].iCursor, p, i, &isAgg); if( needRestoreContext ){ pParse->zAuthContext = zSavedAuthContext; } pTabList = p->pSrc; pWhere = p->pWhere; if( eDest!=SRT_Union && eDest!=SRT_Except && eDest!=SRT_Discard ){ pOrderBy = p->pOrderBy; } pGroupBy = p->pGroupBy; pHaving = p->pHaving; isDistinct = p->isDistinct; } /* 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. */ if( pParent && pParentAgg && flattenSubquery(pParse, pParent, parentTab, *pParentAgg, isAgg) ){ if( isAgg ) *pParentAgg = 1; return rc; } /* Set the limiter. */ computeLimitRegisters(pParse, p); /* Identify column types if we will be using a callback. This ** step is skipped if the output is going to a destination other ** than a callback. ** ** We have to do this separately from the creation of column names ** above because if the pTabList contains views then they will not ** have been resolved and we will not know the column types until ** now. */ if( eDest==SRT_Callback ){ generateColumnTypes(pParse, pTabList, pEList); } /* If the output is destined for a temporary table, open that table. */ if( eDest==SRT_TempTable ){ sqliteVdbeAddOp(v, OP_OpenTemp, iParm, 0); } /* Do an analysis of aggregate expressions. */ sqliteAggregateInfoReset(pParse); if( isAgg || pGroupBy ){ assert( pParse->nAgg==0 ); isAgg = 1; for(i=0; inExpr; i++){ if( sqliteExprAnalyzeAggregates(pParse, pEList->a[i].pExpr) ){ goto select_end; } } if( pGroupBy ){ for(i=0; inExpr; i++){ if( sqliteExprAnalyzeAggregates(pParse, pGroupBy->a[i].pExpr) ){ goto select_end; } } } if( pHaving && sqliteExprAnalyzeAggregates(pParse, pHaving) ){ goto select_end; } if( pOrderBy ){ for(i=0; inExpr; i++){ if( sqliteExprAnalyzeAggregates(pParse, pOrderBy->a[i].pExpr) ){ goto select_end; } } } } /* Reset the aggregator */ if( isAgg ){ sqliteVdbeAddOp(v, OP_AggReset, 0, pParse->nAgg); for(i=0; inAgg; i++){ FuncDef *pFunc; if( (pFunc = pParse->aAgg[i].pFunc)!=0 && pFunc->xFinalize!=0 ){ sqliteVdbeOp3(v, OP_AggInit, 0, i, (char*)pFunc, P3_POINTER); } } if( pGroupBy==0 ){ sqliteVdbeAddOp(v, OP_String, 0, 0); sqliteVdbeAddOp(v, OP_AggFocus, 0, 0); } } /* Initialize the memory cell to NULL */ if( eDest==SRT_Mem ){ sqliteVdbeAddOp(v, OP_String, 0, 0); sqliteVdbeAddOp(v, OP_MemStore, iParm, 1); } /* Open a temporary table to use for the distinct set. */ if( isDistinct ){ distinct = pParse->nTab++; sqliteVdbeAddOp(v, OP_OpenTemp, distinct, 1); }else{ distinct = -1; } /* Begin the database scan */ pWInfo = sqliteWhereBegin(pParse, pTabList, pWhere, 0, pGroupBy ? 0 : &pOrderBy); if( pWInfo==0 ) goto select_end; /* Use the standard inner loop if we are not dealing with ** aggregates */ if( !isAgg ){ if( selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, eDest, iParm, pWInfo->iContinue, pWInfo->iBreak) ){ goto select_end; } } /* If we are dealing with aggregates, then do the special aggregate ** processing. */ else{ AggExpr *pAgg; if( pGroupBy ){ int lbl1; for(i=0; inExpr; i++){ sqliteExprCode(pParse, pGroupBy->a[i].pExpr); } sqliteVdbeAddOp(v, OP_MakeKey, pGroupBy->nExpr, 0); if( pParse->db->file_format>=4 ) sqliteAddKeyType(v, pGroupBy); lbl1 = sqliteVdbeMakeLabel(v); sqliteVdbeAddOp(v, OP_AggFocus, 0, lbl1); for(i=0, pAgg=pParse->aAgg; inAgg; i++, pAgg++){ if( pAgg->isAgg ) continue; sqliteExprCode(pParse, pAgg->pExpr); sqliteVdbeAddOp(v, OP_AggSet, 0, i); } sqliteVdbeResolveLabel(v, lbl1); } for(i=0, pAgg=pParse->aAgg; inAgg; i++, pAgg++){ Expr *pE; int nExpr; FuncDef *pDef; if( !pAgg->isAgg ) continue; assert( pAgg->pFunc!=0 ); assert( pAgg->pFunc->xStep!=0 ); pDef = pAgg->pFunc; pE = pAgg->pExpr; assert( pE!=0 ); assert( pE->op==TK_AGG_FUNCTION ); nExpr = sqliteExprCodeExprList(pParse, pE->pList, pDef->includeTypes); sqliteVdbeAddOp(v, OP_Integer, i, 0); sqliteVdbeOp3(v, OP_AggFunc, 0, nExpr, (char*)pDef, P3_POINTER); } } /* End the database scan loop. */ sqliteWhereEnd(pWInfo); /* If we are processing aggregates, we need to set up a second loop ** over all of the aggregate values and process them. */ if( isAgg ){ int endagg = sqliteVdbeMakeLabel(v); int startagg; startagg = sqliteVdbeAddOp(v, OP_AggNext, 0, endagg); pParse->useAgg = 1; if( pHaving ){ sqliteExprIfFalse(pParse, pHaving, startagg, 1); } if( selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, eDest, iParm, startagg, endagg) ){ goto select_end; } sqliteVdbeAddOp(v, OP_Goto, 0, startagg); sqliteVdbeResolveLabel(v, endagg); sqliteVdbeAddOp(v, OP_Noop, 0, 0); pParse->useAgg = 0; } /* 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(p, v, pEList->nExpr, eDest, iParm); } /* 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 ); sqliteSelectDelete(p); pParent->pSrc->a[parentTab].pSelect = 0; } /* 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: sqliteAggregateInfoReset(pParse); return rc; }