/* ** Generate code for a DELETE FROM statement. ** ** DELETE FROM table_wxyz WHERE a<5 AND b NOT NULL; ** \________/ \________________/ ** pTabList pWhere */ void sqlite3DeleteFrom( Parse *pParse, /* The parser context */ SrcList *pTabList, /* The table from which we should delete things */ Expr *pWhere /* The WHERE clause. May be null */ ){ Vdbe *v; /* The virtual database engine */ Table *pTab; /* The table from which records will be deleted */ int i; /* Loop counter */ WhereInfo *pWInfo; /* Information about the WHERE clause */ Index *pIdx; /* For looping over indices of the table */ int iTabCur; /* Cursor number for the table */ int iDataCur = 0; /* VDBE cursor for the canonical data source */ int iIdxCur = 0; /* Cursor number of the first index */ int nIdx; /* Number of indices */ sqlite3 *db; /* Main database structure */ AuthContext sContext; /* Authorization context */ NameContext sNC; /* Name context to resolve expressions in */ int iDb; /* Database number */ int memCnt = -1; /* Memory cell used for change counting */ int rcauth; /* Value returned by authorization callback */ int eOnePass; /* ONEPASS_OFF or _SINGLE or _MULTI */ int aiCurOnePass[2]; /* The write cursors opened by WHERE_ONEPASS */ u8 *aToOpen = 0; /* Open cursor iTabCur+j if aToOpen[j] is true */ Index *pPk; /* The PRIMARY KEY index on the table */ int iPk = 0; /* First of nPk registers holding PRIMARY KEY value */ i16 nPk = 1; /* Number of columns in the PRIMARY KEY */ int iKey; /* Memory cell holding key of row to be deleted */ i16 nKey; /* Number of memory cells in the row key */ int iEphCur = 0; /* Ephemeral table holding all primary key values */ int iRowSet = 0; /* Register for rowset of rows to delete */ int addrBypass = 0; /* Address of jump over the delete logic */ int addrLoop = 0; /* Top of the delete loop */ int addrEphOpen = 0; /* Instruction to open the Ephemeral table */ int bComplex; /* True if there are triggers or FKs or ** subqueries in the WHERE clause */ #ifndef SQLITE_OMIT_TRIGGER int isView; /* True if attempting to delete from a view */ Trigger *pTrigger; /* List of table triggers, if required */ #endif memset(&sContext, 0, sizeof(sContext)); db = pParse->db; if( pParse->nErr || db->mallocFailed ){ goto delete_from_cleanup; } assert( pTabList->nSrc==1 ); /* Locate the table which we want to delete. This table has to be ** put in an SrcList structure because some of the subroutines we ** will be calling are designed to work with multiple tables and expect ** an SrcList* parameter instead of just a Table* parameter. */ pTab = sqlite3SrcListLookup(pParse, pTabList); if( pTab==0 ) goto delete_from_cleanup; /* Figure out if we have any triggers and if the table being ** deleted from is a view */ #ifndef SQLITE_OMIT_TRIGGER pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0); isView = pTab->pSelect!=0; bComplex = pTrigger || sqlite3FkRequired(pParse, pTab, 0, 0); #else # define pTrigger 0 # define isView 0 #endif #ifdef SQLITE_OMIT_VIEW # undef isView # define isView 0 #endif /* If pTab is really a view, make sure it has been initialized. */ if( sqlite3ViewGetColumnNames(pParse, pTab) ){ goto delete_from_cleanup; } if( sqlite3IsReadOnly(pParse, pTab, (pTrigger?1:0)) ){ goto delete_from_cleanup; } iDb = sqlite3SchemaToIndex(db, pTab->pSchema); assert( iDb<db->nDb ); rcauth = sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0, db->aDb[iDb].zDbSName); assert( rcauth==SQLITE_OK || rcauth==SQLITE_DENY || rcauth==SQLITE_IGNORE ); if( rcauth==SQLITE_DENY ){ goto delete_from_cleanup; } assert(!isView || pTrigger); /* Assign cursor numbers to the table and all its indices. */ assert( pTabList->nSrc==1 ); iTabCur = pTabList->a[0].iCursor = pParse->nTab++; for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){ pParse->nTab++; } /* Start the view context */ if( isView ){ sqlite3AuthContextPush(pParse, &sContext, pTab->zName); } /* Begin generating code. */ v = sqlite3GetVdbe(pParse); if( v==0 ){ goto delete_from_cleanup; } if( pParse->nested==0 ) sqlite3VdbeCountChanges(v); sqlite3BeginWriteOperation(pParse, 1, iDb); /* If we are trying to delete from a view, realize that view into ** an ephemeral table. */ #if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER) if( isView ){ sqlite3MaterializeView(pParse, pTab, pWhere, iTabCur); iDataCur = iIdxCur = iTabCur; } #endif /* Resolve the column names in the WHERE clause. */ memset(&sNC, 0, sizeof(sNC)); sNC.pParse = pParse; sNC.pSrcList = pTabList; if( sqlite3ResolveExprNames(&sNC, pWhere) ){ goto delete_from_cleanup; } /* Initialize the counter of the number of rows deleted, if ** we are counting rows. */ if( db->flags & SQLITE_CountRows ){ memCnt = ++pParse->nMem; sqlite3VdbeAddOp2(v, OP_Integer, 0, memCnt); } #ifndef SQLITE_OMIT_TRUNCATE_OPTIMIZATION /* Special case: A DELETE without a WHERE clause deletes everything. ** It is easier just to erase the whole table. Prior to version 3.6.5, ** this optimization caused the row change count (the value returned by ** API function sqlite3_count_changes) to be set incorrectly. */ if( rcauth==SQLITE_OK && pWhere==0 && !bComplex && !IsVirtual(pTab) #ifdef SQLITE_ENABLE_PREUPDATE_HOOK && db->xPreUpdateCallback==0 #endif ){ assert( !isView ); sqlite3TableLock(pParse, iDb, pTab->tnum, 1, pTab->zName); if( HasRowid(pTab) ){ sqlite3VdbeAddOp4(v, OP_Clear, pTab->tnum, iDb, memCnt, pTab->zName, P4_STATIC); } for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ assert( pIdx->pSchema==pTab->pSchema ); sqlite3VdbeAddOp2(v, OP_Clear, pIdx->tnum, iDb); } }else #endif /* SQLITE_OMIT_TRUNCATE_OPTIMIZATION */ { u16 wcf = WHERE_ONEPASS_DESIRED|WHERE_DUPLICATES_OK|WHERE_SEEK_TABLE; if( sNC.ncFlags & NC_VarSelect ) bComplex = 1; wcf |= (bComplex ? 0 : WHERE_ONEPASS_MULTIROW); if( HasRowid(pTab) ){ /* For a rowid table, initialize the RowSet to an empty set */ pPk = 0; nPk = 1; iRowSet = ++pParse->nMem; sqlite3VdbeAddOp2(v, OP_Null, 0, iRowSet); }else{ /* For a WITHOUT ROWID table, create an ephemeral table used to ** hold all primary keys for rows to be deleted. */ pPk = sqlite3PrimaryKeyIndex(pTab); assert( pPk!=0 ); nPk = pPk->nKeyCol; iPk = pParse->nMem+1; pParse->nMem += nPk; iEphCur = pParse->nTab++; addrEphOpen = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iEphCur, nPk); sqlite3VdbeSetP4KeyInfo(pParse, pPk); } /* Construct a query to find the rowid or primary key for every row ** to be deleted, based on the WHERE clause. Set variable eOnePass ** to indicate the strategy used to implement this delete: ** ** ONEPASS_OFF: Two-pass approach - use a FIFO for rowids/PK values. ** ONEPASS_SINGLE: One-pass approach - at most one row deleted. ** ONEPASS_MULTI: One-pass approach - any number of rows may be deleted. */ pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, 0, wcf, iTabCur+1); if( pWInfo==0 ) goto delete_from_cleanup; eOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass); assert( IsVirtual(pTab)==0 || eOnePass!=ONEPASS_MULTI ); assert( IsVirtual(pTab) || bComplex || eOnePass!=ONEPASS_OFF ); /* Keep track of the number of rows to be deleted */ if( db->flags & SQLITE_CountRows ){ sqlite3VdbeAddOp2(v, OP_AddImm, memCnt, 1); } /* Extract the rowid or primary key for the current row */ if( pPk ){ for(i=0; i<nPk; i++){ assert( pPk->aiColumn[i]>=0 ); sqlite3ExprCodeGetColumnOfTable(v, pTab, iTabCur, pPk->aiColumn[i], iPk+i); } iKey = iPk; }else{ iKey = pParse->nMem + 1; iKey = sqlite3ExprCodeGetColumn(pParse, pTab, -1, iTabCur, iKey, 0); if( iKey>pParse->nMem ) pParse->nMem = iKey; } if( eOnePass!=ONEPASS_OFF ){ /* For ONEPASS, no need to store the rowid/primary-key. There is only ** one, so just keep it in its register(s) and fall through to the ** delete code. */ nKey = nPk; /* OP_Found will use an unpacked key */ aToOpen = sqlite3DbMallocRawNN(db, nIdx+2); if( aToOpen==0 ){ sqlite3WhereEnd(pWInfo); goto delete_from_cleanup; } memset(aToOpen, 1, nIdx+1); aToOpen[nIdx+1] = 0; if( aiCurOnePass[0]>=0 ) aToOpen[aiCurOnePass[0]-iTabCur] = 0; if( aiCurOnePass[1]>=0 ) aToOpen[aiCurOnePass[1]-iTabCur] = 0; if( addrEphOpen ) sqlite3VdbeChangeToNoop(v, addrEphOpen); }else{ if( pPk ){ /* Add the PK key for this row to the temporary table */ iKey = ++pParse->nMem; nKey = 0; /* Zero tells OP_Found to use a composite key */ sqlite3VdbeAddOp4(v, OP_MakeRecord, iPk, nPk, iKey, sqlite3IndexAffinityStr(pParse->db, pPk), nPk); sqlite3VdbeAddOp2(v, OP_IdxInsert, iEphCur, iKey); }else{ /* Add the rowid of the row to be deleted to the RowSet */ nKey = 1; /* OP_Seek always uses a single rowid */ sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, iKey); } } /* If this DELETE cannot use the ONEPASS strategy, this is the ** end of the WHERE loop */ if( eOnePass!=ONEPASS_OFF ){ addrBypass = sqlite3VdbeMakeLabel(v); }else{ sqlite3WhereEnd(pWInfo); } /* Unless this is a view, open cursors for the table we are ** deleting from and all its indices. If this is a view, then the ** only effect this statement has is to fire the INSTEAD OF ** triggers. */ if( !isView ){ int iAddrOnce = 0; if( eOnePass==ONEPASS_MULTI ){ iAddrOnce = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v); } testcase( IsVirtual(pTab) ); sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenWrite, OPFLAG_FORDELETE, iTabCur, aToOpen, &iDataCur, &iIdxCur); assert( pPk || IsVirtual(pTab) || iDataCur==iTabCur ); assert( pPk || IsVirtual(pTab) || iIdxCur==iDataCur+1 ); if( eOnePass==ONEPASS_MULTI ) sqlite3VdbeJumpHere(v, iAddrOnce); } /* Set up a loop over the rowids/primary-keys that were found in the ** where-clause loop above. */ if( eOnePass!=ONEPASS_OFF ){ assert( nKey==nPk ); /* OP_Found will use an unpacked key */ if( !IsVirtual(pTab) && aToOpen[iDataCur-iTabCur] ){ assert( pPk!=0 || pTab->pSelect!=0 ); sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, addrBypass, iKey, nKey); VdbeCoverage(v); } }else if( pPk ){ addrLoop = sqlite3VdbeAddOp1(v, OP_Rewind, iEphCur); VdbeCoverage(v); sqlite3VdbeAddOp2(v, OP_RowKey, iEphCur, iKey); assert( nKey==0 ); /* OP_Found will use a composite key */ }else{ addrLoop = sqlite3VdbeAddOp3(v, OP_RowSetRead, iRowSet, 0, iKey); VdbeCoverage(v); assert( nKey==1 ); } /* Delete the row */ #ifndef SQLITE_OMIT_VIRTUALTABLE if( IsVirtual(pTab) ){ const char *pVTab = (const char *)sqlite3GetVTable(db, pTab); sqlite3VtabMakeWritable(pParse, pTab); sqlite3VdbeAddOp4(v, OP_VUpdate, 0, 1, iKey, pVTab, P4_VTAB); sqlite3VdbeChangeP5(v, OE_Abort); assert( eOnePass==ONEPASS_OFF || eOnePass==ONEPASS_SINGLE ); sqlite3MayAbort(pParse); if( eOnePass==ONEPASS_SINGLE && sqlite3IsToplevel(pParse) ){ pParse->isMultiWrite = 0; } }else #endif { int count = (pParse->nested==0); /* True to count changes */ int iIdxNoSeek = -1; if( bComplex==0 && aiCurOnePass[1]!=iDataCur ){ iIdxNoSeek = aiCurOnePass[1]; } sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur, iKey, nKey, count, OE_Default, eOnePass, iIdxNoSeek); } /* End of the loop over all rowids/primary-keys. */ if( eOnePass!=ONEPASS_OFF ){ sqlite3VdbeResolveLabel(v, addrBypass); sqlite3WhereEnd(pWInfo); }else if( pPk ){ sqlite3VdbeAddOp2(v, OP_Next, iEphCur, addrLoop+1); VdbeCoverage(v); sqlite3VdbeJumpHere(v, addrLoop); }else{ sqlite3VdbeGoto(v, addrLoop); sqlite3VdbeJumpHere(v, addrLoop); } /* Close the cursors open on the table and its indexes. */ if( !isView && !IsVirtual(pTab) ){ if( !pPk ) sqlite3VdbeAddOp1(v, OP_Close, iDataCur); for(i=0, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){ sqlite3VdbeAddOp1(v, OP_Close, iIdxCur + i); } } } /* End non-truncate path */ /* Update the sqlite_sequence table by storing the content of the ** maximum rowid counter values recorded while inserting into ** autoincrement tables. */ if( pParse->nested==0 && pParse->pTriggerTab==0 ){ sqlite3AutoincrementEnd(pParse); } /* Return the number of rows that were deleted. If this routine is ** generating code because of a call to sqlite3NestedParse(), do not ** invoke the callback function. */ if( (db->flags&SQLITE_CountRows) && !pParse->nested && !pParse->pTriggerTab ){ sqlite3VdbeAddOp2(v, OP_ResultRow, memCnt, 1); sqlite3VdbeSetNumCols(v, 1); sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows deleted", SQLITE_STATIC); } delete_from_cleanup: sqlite3AuthContextPop(&sContext); sqlite3SrcListDelete(db, pTabList); sqlite3ExprDelete(db, pWhere); sqlite3DbFree(db, aToOpen); return; }
/* ** Generate code for a DELETE FROM statement. ** ** DELETE FROM table_wxyz WHERE a<5 AND b NOT NULL; ** \________/ \________________/ ** pTabList pWhere */ void sqlite3DeleteFrom( Parse *pParse, /* The parser context */ SrcList *pTabList, /* The table from which we should delete things */ Expr *pWhere /* The WHERE clause. May be null */ ){ Vdbe *v; /* The virtual database engine */ Table *pTab; /* The table from which records will be deleted */ const char *zDb; /* Name of database holding pTab */ int end, addr = 0; /* A couple addresses of generated code */ int i; /* Loop counter */ WhereInfo *pWInfo; /* Information about the WHERE clause */ Index *pIdx; /* For looping over indices of the table */ int iCur; /* VDBE Cursor number for pTab */ sqlite3 *db; /* Main database structure */ AuthContext sContext; /* Authorization context */ NameContext sNC; /* Name context to resolve expressions in */ int iDb; /* Database number */ int memCnt = -1; /* Memory cell used for change counting */ int rcauth; /* Value returned by authorization callback */ #ifndef SQLITE_OMIT_TRIGGER int isView; /* True if attempting to delete from a view */ Trigger *pTrigger; /* List of table triggers, if required */ #endif memset(&sContext, 0, sizeof(sContext)); db = pParse->db; if( pParse->nErr || db->mallocFailed ){ goto delete_from_cleanup; } assert( pTabList->nSrc==1 ); /* Locate the table which we want to delete. This table has to be ** put in an SrcList structure because some of the subroutines we ** will be calling are designed to work with multiple tables and expect ** an SrcList* parameter instead of just a Table* parameter. */ pTab = sqlite3SrcListLookup(pParse, pTabList); if( pTab==0 ) goto delete_from_cleanup; /* Figure out if we have any triggers and if the table being ** deleted from is a view */ #ifndef SQLITE_OMIT_TRIGGER pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0); isView = pTab->pSelect!=0; #else # define pTrigger 0 # define isView 0 #endif #ifdef SQLITE_OMIT_VIEW # undef isView # define isView 0 #endif /* If pTab is really a view, make sure it has been initialized. */ if( sqlite3ViewGetColumnNames(pParse, pTab) ){ goto delete_from_cleanup; } if( sqlite3IsReadOnly(pParse, pTab, (pTrigger?1:0)) ){ goto delete_from_cleanup; } iDb = sqlite3SchemaToIndex(db, pTab->pSchema); assert( iDb<db->nDb ); zDb = db->aDb[iDb].zName; rcauth = sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0, zDb); assert( rcauth==SQLITE_OK || rcauth==SQLITE_DENY || rcauth==SQLITE_IGNORE ); if( rcauth==SQLITE_DENY ){ goto delete_from_cleanup; } assert(!isView || pTrigger); /* Assign cursor number to the table and all its indices. */ assert( pTabList->nSrc==1 ); iCur = pTabList->a[0].iCursor = pParse->nTab++; for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ pParse->nTab++; } /* Start the view context */ if( isView ){ sqlite3AuthContextPush(pParse, &sContext, pTab->zName); } /* Begin generating code. */ v = sqlite3GetVdbe(pParse); if( v==0 ){ goto delete_from_cleanup; } if( pParse->nested==0 ) sqlite3VdbeCountChanges(v); sqlite3BeginWriteOperation(pParse, 1, iDb); /* If we are trying to delete from a view, realize that view into ** a ephemeral table. */ #if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER) if( isView ){ sqlite3MaterializeView(pParse, pTab, pWhere, iCur); } #endif /* Resolve the column names in the WHERE clause. */ memset(&sNC, 0, sizeof(sNC)); sNC.pParse = pParse; sNC.pSrcList = pTabList; if( sqlite3ResolveExprNames(&sNC, pWhere) ){ goto delete_from_cleanup; } /* Initialize the counter of the number of rows deleted, if ** we are counting rows. */ if( db->flags & SQLITE_CountRows ){ memCnt = ++pParse->nMem; sqlite3VdbeAddOp2(v, OP_Integer, 0, memCnt); } #ifndef SQLITE_OMIT_TRUNCATE_OPTIMIZATION /* Special case: A DELETE without a WHERE clause deletes everything. ** It is easier just to erase the whole table. Prior to version 3.6.5, ** this optimization caused the row change count (the value returned by ** API function sqlite3_count_changes) to be set incorrectly. */ if( rcauth==SQLITE_OK && pWhere==0 && !pTrigger && !IsVirtual(pTab) && 0==sqlite3FkRequired(pParse, pTab, 0, 0) ){ assert( !isView ); sqlite3VdbeAddOp4(v, OP_Clear, pTab->tnum, iDb, memCnt, pTab->zName, P4_STATIC); for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ assert( pIdx->pSchema==pTab->pSchema ); sqlite3VdbeAddOp2(v, OP_Clear, pIdx->tnum, iDb); } }else #endif /* SQLITE_OMIT_TRUNCATE_OPTIMIZATION */ /* The usual case: There is a WHERE clause so we have to scan through ** the table and pick which records to delete. */ { int iRowSet = ++pParse->nMem; /* Register for rowset of rows to delete */ int iRowid = ++pParse->nMem; /* Used for storing rowid values. */ int regRowid; /* Actual register containing rowids */ /* Collect rowids of every row to be deleted. */ sqlite3VdbeAddOp2(v, OP_Null, 0, iRowSet); pWInfo = sqlite3WhereBegin( pParse, pTabList, pWhere, 0, 0, WHERE_DUPLICATES_OK, 0 ); if( pWInfo==0 ) goto delete_from_cleanup; regRowid = sqlite3ExprCodeGetColumn(pParse, pTab, -1, iCur, iRowid, 0); sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, regRowid); if( db->flags & SQLITE_CountRows ){ sqlite3VdbeAddOp2(v, OP_AddImm, memCnt, 1); } sqlite3WhereEnd(pWInfo); /* Delete every item whose key was written to the list during the ** database scan. We have to delete items after the scan is complete ** because deleting an item can change the scan order. */ end = sqlite3VdbeMakeLabel(v); /* Unless this is a view, open cursors for the table we are ** deleting from and all its indices. If this is a view, then the ** only effect this statement has is to fire the INSTEAD OF ** triggers. */ if( !isView ){ sqlite3OpenTableAndIndices(pParse, pTab, iCur, OP_OpenWrite); } addr = sqlite3VdbeAddOp3(v, OP_RowSetRead, iRowSet, end, iRowid); /* Delete the row */ #ifndef SQLITE_OMIT_VIRTUALTABLE if( IsVirtual(pTab) ){ const char *pVTab = (const char *)sqlite3GetVTable(db, pTab); sqlite3VtabMakeWritable(pParse, pTab); sqlite3VdbeAddOp4(v, OP_VUpdate, 0, 1, iRowid, pVTab, P4_VTAB); sqlite3VdbeChangeP5(v, OE_Abort); sqlite3MayAbort(pParse); }else #endif { int count = (pParse->nested==0); /* True to count changes */ sqlite3GenerateRowDelete(pParse, pTab, iCur, iRowid, count, pTrigger, OE_Default); } /* End of the delete loop */ sqlite3VdbeAddOp2(v, OP_Goto, 0, addr); sqlite3VdbeResolveLabel(v, end); /* Close the cursors open on the table and its indexes. */ if( !isView && !IsVirtual(pTab) ){ for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){ sqlite3VdbeAddOp2(v, OP_Close, iCur + i, pIdx->tnum); } sqlite3VdbeAddOp1(v, OP_Close, iCur); } } /* Update the sqlite_sequence table by storing the content of the ** maximum rowid counter values recorded while inserting into ** autoincrement tables. */ if( pParse->nested==0 && pParse->pTriggerTab==0 ){ sqlite3AutoincrementEnd(pParse); } /* Return the number of rows that were deleted. If this routine is ** generating code because of a call to sqlite3NestedParse(), do not ** invoke the callback function. */ if( (db->flags&SQLITE_CountRows) && !pParse->nested && !pParse->pTriggerTab ){ sqlite3VdbeAddOp2(v, OP_ResultRow, memCnt, 1); sqlite3VdbeSetNumCols(v, 1); sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows deleted", SQLITE_STATIC); } delete_from_cleanup: sqlite3AuthContextPop(&sContext); sqlite3SrcListDelete(db, pTabList); sqlite3ExprDelete(db, pWhere); return; }