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Diffstat (limited to 'src/libs/sqlite2/select.c')
| -rw-r--r-- | src/libs/sqlite2/select.c | 2434 |
1 files changed, 2434 insertions, 0 deletions
diff --git a/src/libs/sqlite2/select.c b/src/libs/sqlite2/select.c new file mode 100644 index 00000000..4cf03606 --- /dev/null +++ b/src/libs/sqlite2/select.c @@ -0,0 +1,2434 @@ +/* +** 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 875429 2008-10-24 12:20:41Z cgilles $ +*/ +#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; j<sizeof(keywords)/sizeof(keywords[0]); j++){ + if( p->n==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; i<pTab->nCol; 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; i<pSrc->nSrc-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; j<pTab->nCol; 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( i<pSrc->nSrc-1 ); + pList = pTerm->pUsing; + for(j=0; j<pList->nId; 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; i<pOrderBy->nExpr; 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; i<nColumn; i++){ + zType[i] = sqliteExprType(pEList->a[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; i<nColumn; i++){ + sqliteVdbeAddOp(v, OP_Column, srcTab, i); + } + }else{ + nColumn = pEList->nExpr; + for(i=0; i<pEList->nExpr; 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; i<nColumn; i++){ + sqliteVdbeAddOp(v, OP_Column, -1-i, i); + } + sqliteVdbeAddOp(v, OP_Gosub, 0, iParm); + sqliteVdbeAddOp(v, OP_Pop, 1, 0); + break; + } + default: { + /* Do nothing */ + break; + } + } + sqliteVdbeAddOp(v, OP_Goto, 0, addr); + sqliteVdbeResolveLabel(v, end2); + sqliteVdbeAddOp(v, OP_Pop, 1, 0); + sqliteVdbeResolveLabel(v, end1); + sqliteVdbeAddOp(v, OP_SortReset, 0, 0); +} + +/* +** Generate code that will tell the VDBE the datatypes of +** columns in the result set. +** +** This routine only generates code if the "PRAGMA show_datatypes=on" +** has been executed. The datatypes are reported out in the azCol +** parameter to the callback function. The first N azCol[] entries +** are the names of the columns, and the second N entries are the +** datatypes for the columns. +** +** The "datatype" for a result that is a column of a type is the +** datatype definition extracted from the CREATE TABLE statement. +** The datatype for an expression is either TEXT or NUMERIC. The +** datatype for a ROWID field is INTEGER. +*/ +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, j; + for(i=0; i<pEList->nExpr; 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; j<pTabList->nSrc && pTabList->a[j].iCursor!=p->iTable; j++){} + assert( j<pTabList->nSrc ); + pTab = pTabList->a[j].pTab; + if( iCol<0 ) iCol = pTab->iPKey; + assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) ); + if( iCol<0 ){ + 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; i<pEList->nExpr; 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; j<pTabList->nSrc && pTabList->a[j].iCursor!=p->iTable; j++){} + assert( j<pTabList->nSrc ); + pTab = pTabList->a[j].pTab; + if( iCol<0 ) iCol = pTab->iPKey; + assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) ); + if( iCol<0 ){ + zCol = "_ROWID_"; + }else{ + zCol = pTab->aCol[iCol].zName; + } + if( !shortNames && !fullNames && p->span.z && p->span.z[0] ){ + 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; i<pTab->nCol; 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; j<i; j++){ + if( sqliteStrICmp(aCol[j].zName, aCol[i].zName)==0 ){ + int n; + char zBuf[30]; + sprintf(zBuf,"_%d",++cnt); + n = strlen(zBuf); + sqliteSetNString(&aCol[i].zName, pR->token.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; i<pTabList->nSrc; 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; k<pEList->nExpr; k++){ + Expr *pE = pEList->a[k].pExpr; + if( pE->op==TK_ALL ) break; + if( pE->op==TK_DOT && pE->pRight && pE->pRight->op==TK_ALL + && pE->pLeft && pE->pLeft->op==TK_ID ) break; + } + rc = 0; + if( k<pEList->nExpr ){ + /* + ** If we get here it means the result set contains one or more "*" + ** operators that need to be expanded. Loop through each expression + ** in the result set and expand them one by one. + */ + struct ExprList_item *a = pEList->a; + ExprList *pNew = 0; + for(k=0; k<pEList->nExpr; k++){ + Expr *pE = a[k].pExpr; + if( pE->op!=TK_ALL && + (pE->op!=TK_DOT || pE->pRight==0 || pE->pRight->op!=TK_ALL) ){ + /* This particular expression does not need to be expanded. + */ + pNew = 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; i<pTabList->nSrc; 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; j<pTab->nCol; 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; i<pSrc->nSrc; 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; i<pOrderBy->nExpr; 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; i<pOrderBy->nExpr; 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 && j<pEList->nExpr; j++){ + if( pEList->a[j].zName && (pE->op==TK_ID || pE->op==TK_STRING) ){ + char *zName, *zLabel; + zName = pEList->a[j].zName; + 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; i<pOrderBy->nExpr; i++){ + pOrderBy->a[i].pExpr->dataType = SQLITE_SO_TEXT; + } + return; + } + multiSelectSortOrder(p->pPrior, pOrderBy); + pEList = p->pEList; + for(i=0; i<pOrderBy->nExpr; 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->iColumn<pEList->nExpr ); + assert( pExpr->pLeft==0 && pExpr->pRight==0 && pExpr->pList==0 ); + pNew = pEList->a[pExpr->iColumn].pExpr; + assert( pNew!=0 ); + pExpr->op = pNew->op; + 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; i<pList->nExpr; 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 && iFrom<pSrc->nSrc ); + 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; i<nSubSrc; i++){ + pSrc = sqliteSrcListAppend(pSrc, 0, 0); + } + p->pSrc = pSrc; + for(i=pSrc->nSrc-1; i-extra>=iFrom; i--){ + pSrc->a[i] = pSrc->a[i-extra]; + } + } + for(i=0; i<nSubSrc; i++){ + pSrc->a[i+iFrom] = pSubSrc->a[i]; + memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i])); + } + pSrc->a[iFrom+nSubSrc-1].jointype = jointype; + } + + /* Now begin substituting subquery result set expressions for + ** references to the iParent in the outer query. + ** + ** Example: + ** + ** SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b; + ** \ \_____________ subquery __________/ / + ** \_____________________ outer query ______________________________/ + ** + ** We look at every expression in the outer query and every place we see + ** "a" we substitute "x*3" and every place we see "b" we substitute "y+10". + */ + substExprList(p->pEList, iParent, pSub->pEList); + pList = p->pEList; + for(i=0; i<pList->nExpr; i++){ + Expr *pExpr; + if( pList->a[i].zName==0 && (pExpr = pList->a[i].pExpr)->span.z!=0 ){ + pList->a[i].zName = sqliteStrNDup(pExpr->span.z, pExpr->span.n); + } + } + if( isAgg ){ + substExprList(p->pGroupBy, iParent, pSub->pEList); + substExpr(p->pHaving, iParent, pSub->pEList); + } + if( pSub->pOrderBy ){ + assert( p->pOrderBy==0 ); + p->pOrderBy = pSub->pOrderBy; + pSub->pOrderBy = 0; + }else if( p->pOrderBy ){ + substExprList(p->pOrderBy, iParent, pSub->pEList); + } + if( pSub->pWhere ){ + pWhere = 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; i<pEList->nExpr; 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; i<pOrderBy->nExpr; 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; i<pGroupBy->nExpr; 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; i<pTabList->nSrc; 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; i<pEList->nExpr; i++){ + if( sqliteExprAnalyzeAggregates(pParse, pEList->a[i].pExpr) ){ + goto select_end; + } + } + if( pGroupBy ){ + for(i=0; i<pGroupBy->nExpr; i++){ + if( sqliteExprAnalyzeAggregates(pParse, pGroupBy->a[i].pExpr) ){ + goto select_end; + } + } + } + if( pHaving && sqliteExprAnalyzeAggregates(pParse, pHaving) ){ + goto select_end; + } + if( pOrderBy ){ + for(i=0; i<pOrderBy->nExpr; 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; i<pParse->nAgg; 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; i<pGroupBy->nExpr; 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; i<pParse->nAgg; 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; i<pParse->nAgg; 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; +} |