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Diffstat (limited to 'src/sqlite/delete.c')
| -rw-r--r-- | src/sqlite/delete.c | 447 |
1 files changed, 447 insertions, 0 deletions
diff --git a/src/sqlite/delete.c b/src/sqlite/delete.c new file mode 100644 index 0000000..2908885 --- /dev/null +++ b/src/sqlite/delete.c @@ -0,0 +1,447 @@ +/* +** 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 +** in order to generate code for DELETE FROM statements. +** +** $Id: delete.c,v 1.1.1.1 2006/02/03 20:35:13 hoganrobert Exp $ +*/ +#include "sqliteInt.h" + +/* +** Look up every table that is named in pSrc. If any table is not found, +** add an error message to pParse->zErrMsg and return NULL. If all tables +** are found, return a pointer to the last table. +*/ +Table *sqlite3SrcListLookup(Parse *pParse, SrcList *pSrc){ + Table *pTab = 0; + int i; + struct SrcList_item *pItem; + for(i=0, pItem=pSrc->a; i<pSrc->nSrc; i++, pItem++){ + pTab = sqlite3LocateTable(pParse, pItem->zName, pItem->zDatabase); + sqlite3DeleteTable(pParse->db, pItem->pTab); + pItem->pTab = pTab; + if( pTab ){ + pTab->nRef++; + } + } + return pTab; +} + +/* +** Check to make sure the given table is writable. If it is not +** writable, generate an error message and return 1. If it is +** writable return 0; +*/ +int sqlite3IsReadOnly(Parse *pParse, Table *pTab, int viewOk){ + if( pTab->readOnly && (pParse->db->flags & SQLITE_WriteSchema)==0 + && pParse->nested==0 ){ + sqlite3ErrorMsg(pParse, "table %s may not be modified", pTab->zName); + return 1; + } +#ifndef SQLITE_OMIT_VIEW + if( !viewOk && pTab->pSelect ){ + sqlite3ErrorMsg(pParse,"cannot modify %s because it is a view",pTab->zName); + return 1; + } +#endif + return 0; +} + +/* +** Generate code that will open a table for reading. +*/ +void sqlite3OpenTableForReading( + Vdbe *v, /* Generate code into this VDBE */ + int iCur, /* The cursor number of the table */ + Table *pTab /* The table to be opened */ +){ + sqlite3VdbeAddOp(v, OP_Integer, pTab->iDb, 0); + sqlite3VdbeAddOp(v, OP_OpenRead, iCur, pTab->tnum); + VdbeComment((v, "# %s", pTab->zName)); + sqlite3VdbeAddOp(v, OP_SetNumColumns, iCur, pTab->nCol); +} + + +/* +** 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 */ + int oldIdx = -1; /* Cursor for the OLD table of AFTER triggers */ + NameContext sNC; /* Name context to resolve expressions in */ + +#ifndef SQLITE_OMIT_TRIGGER + int isView; /* True if attempting to delete from a view */ + int triggers_exist = 0; /* True if any triggers exist */ +#endif + + sContext.pParse = 0; + if( pParse->nErr || sqlite3_malloc_failed ){ + goto delete_from_cleanup; + } + db = pParse->db; + 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 + triggers_exist = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0); + isView = pTab->pSelect!=0; +#else +# define triggers_exist 0 +# define isView 0 +#endif +#ifdef SQLITE_OMIT_VIEW +# undef isView +# define isView 0 +#endif + + if( sqlite3IsReadOnly(pParse, pTab, triggers_exist) ){ + goto delete_from_cleanup; + } + assert( pTab->iDb<db->nDb ); + zDb = db->aDb[pTab->iDb].zName; + if( sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0, zDb) ){ + goto delete_from_cleanup; + } + + /* If pTab is really a view, make sure it has been initialized. + */ + if( isView && sqlite3ViewGetColumnNames(pParse, pTab) ){ + goto delete_from_cleanup; + } + + /* Allocate a cursor used to store the old.* data for a trigger. + */ + if( triggers_exist ){ + oldIdx = pParse->nTab++; + } + + /* Resolve the column names in the WHERE clause. + */ + assert( pTabList->nSrc==1 ); + iCur = pTabList->a[0].iCursor = pParse->nTab++; + memset(&sNC, 0, sizeof(sNC)); + sNC.pParse = pParse; + sNC.pSrcList = pTabList; + if( sqlite3ExprResolveNames(&sNC, pWhere) ){ + goto delete_from_cleanup; + } + + /* 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, triggers_exist, pTab->iDb); + + /* If we are trying to delete from a view, construct that view into + ** a temporary table. + */ + if( isView ){ + Select *pView = sqlite3SelectDup(pTab->pSelect); + sqlite3Select(pParse, pView, SRT_TempTable, iCur, 0, 0, 0, 0); + sqlite3SelectDelete(pView); + } + + /* Initialize the counter of the number of rows deleted, if + ** we are counting rows. + */ + if( db->flags & SQLITE_CountRows ){ + sqlite3VdbeAddOp(v, OP_Integer, 0, 0); + } + + /* Special case: A DELETE without a WHERE clause deletes everything. + ** It is easier just to erase the whole table. Note, however, that + ** this means that the row change count will be incorrect. + */ + if( pWhere==0 && !triggers_exist ){ + if( db->flags & SQLITE_CountRows ){ + /* If counting rows deleted, just count the total number of + ** entries in the table. */ + int endOfLoop = sqlite3VdbeMakeLabel(v); + int addr; + if( !isView ){ + sqlite3OpenTableForReading(v, iCur, pTab); + } + sqlite3VdbeAddOp(v, OP_Rewind, iCur, sqlite3VdbeCurrentAddr(v)+2); + addr = sqlite3VdbeAddOp(v, OP_AddImm, 1, 0); + sqlite3VdbeAddOp(v, OP_Next, iCur, addr); + sqlite3VdbeResolveLabel(v, endOfLoop); + sqlite3VdbeAddOp(v, OP_Close, iCur, 0); + } + if( !isView ){ + sqlite3VdbeAddOp(v, OP_Clear, pTab->tnum, pTab->iDb); + for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ + sqlite3VdbeAddOp(v, OP_Clear, pIdx->tnum, pIdx->iDb); + } + } + } + + /* The usual case: There is a WHERE clause so we have to scan through + ** the table and pick which records to delete. + */ + else{ + /* Ensure all required collation sequences are available. */ + for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ + if( sqlite3CheckIndexCollSeq(pParse, pIdx) ){ + goto delete_from_cleanup; + } + } + + /* Begin the database scan + */ + pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0); + if( pWInfo==0 ) goto delete_from_cleanup; + + /* Remember the rowid of every item to be deleted. + */ + sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0); + sqlite3VdbeAddOp(v, OP_ListWrite, 0, 0); + if( db->flags & SQLITE_CountRows ){ + sqlite3VdbeAddOp(v, OP_AddImm, 1, 0); + } + + /* End the database scan loop. + */ + sqlite3WhereEnd(pWInfo); + + /* Open the pseudo-table used to store OLD if there are triggers. + */ + if( triggers_exist ){ + sqlite3VdbeAddOp(v, OP_OpenPseudo, oldIdx, 0); + sqlite3VdbeAddOp(v, OP_SetNumColumns, oldIdx, pTab->nCol); + } + + /* 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. + */ + sqlite3VdbeAddOp(v, OP_ListRewind, 0, 0); + end = sqlite3VdbeMakeLabel(v); + + /* This is the beginning of the delete loop when there are + ** row triggers. + */ + if( triggers_exist ){ + addr = sqlite3VdbeAddOp(v, OP_ListRead, 0, end); + if( !isView ){ + sqlite3VdbeAddOp(v, OP_Dup, 0, 0); + sqlite3OpenTableForReading(v, iCur, pTab); + } + sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0); + sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0); + sqlite3VdbeAddOp(v, OP_RowData, iCur, 0); + sqlite3VdbeAddOp(v, OP_Insert, oldIdx, 0); + if( !isView ){ + sqlite3VdbeAddOp(v, OP_Close, iCur, 0); + } + + (void)sqlite3CodeRowTrigger(pParse, TK_DELETE, 0, TRIGGER_BEFORE, pTab, + -1, oldIdx, (pParse->trigStack)?pParse->trigStack->orconf:OE_Default, + addr); + } + + if( !isView ){ + /* Open cursors for the table we are deleting from and all its + ** indices. If there are row triggers, this happens inside the + ** OP_ListRead loop because the cursor have to all be closed + ** before the trigger fires. If there are no row triggers, the + ** cursors are opened only once on the outside the loop. + */ + sqlite3OpenTableAndIndices(pParse, pTab, iCur, OP_OpenWrite); + + /* This is the beginning of the delete loop when there are no + ** row triggers */ + if( !triggers_exist ){ + addr = sqlite3VdbeAddOp(v, OP_ListRead, 0, end); + } + + /* Delete the row */ + sqlite3GenerateRowDelete(db, v, pTab, iCur, pParse->nested==0); + } + + /* If there are row triggers, close all cursors then invoke + ** the AFTER triggers + */ + if( triggers_exist ){ + if( !isView ){ + for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){ + sqlite3VdbeAddOp(v, OP_Close, iCur + i, pIdx->tnum); + } + sqlite3VdbeAddOp(v, OP_Close, iCur, 0); + } + (void)sqlite3CodeRowTrigger(pParse, TK_DELETE, 0, TRIGGER_AFTER, pTab, -1, + oldIdx, (pParse->trigStack)?pParse->trigStack->orconf:OE_Default, + addr); + } + + /* End of the delete loop */ + sqlite3VdbeAddOp(v, OP_Goto, 0, addr); + sqlite3VdbeResolveLabel(v, end); + sqlite3VdbeAddOp(v, OP_ListReset, 0, 0); + + /* Close the cursors after the loop if there are no row triggers */ + if( !triggers_exist ){ + for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){ + sqlite3VdbeAddOp(v, OP_Close, iCur + i, pIdx->tnum); + } + sqlite3VdbeAddOp(v, OP_Close, iCur, 0); + } + } + + /* + ** 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==0 && !pParse->trigStack ){ + sqlite3VdbeAddOp(v, OP_Callback, 1, 0); + sqlite3VdbeSetNumCols(v, 1); + sqlite3VdbeSetColName(v, 0, "rows deleted", P3_STATIC); + } + +delete_from_cleanup: + sqlite3AuthContextPop(&sContext); + sqlite3SrcListDelete(pTabList); + sqlite3ExprDelete(pWhere); + return; +} + +/* +** This routine generates VDBE code that causes a single row of a +** single table to be deleted. +** +** The VDBE must be in a particular state when this routine is called. +** These are the requirements: +** +** 1. A read/write cursor pointing to pTab, the table containing the row +** to be deleted, must be opened as cursor number "base". +** +** 2. Read/write cursors for all indices of pTab must be open as +** cursor number base+i for the i-th index. +** +** 3. The record number of the row to be deleted must be on the top +** of the stack. +** +** This routine pops the top of the stack to remove the record number +** and then generates code to remove both the table record and all index +** entries that point to that record. +*/ +void sqlite3GenerateRowDelete( + sqlite3 *db, /* The database containing the index */ + Vdbe *v, /* Generate code into this VDBE */ + Table *pTab, /* Table containing the row to be deleted */ + int iCur, /* Cursor number for the table */ + int count /* Increment the row change counter */ +){ + int addr; + addr = sqlite3VdbeAddOp(v, OP_NotExists, iCur, 0); + sqlite3GenerateRowIndexDelete(db, v, pTab, iCur, 0); + sqlite3VdbeAddOp(v, OP_Delete, iCur, (count?OPFLAG_NCHANGE:0)); + sqlite3VdbeChangeP2(v, addr, sqlite3VdbeCurrentAddr(v)); +} + +/* +** This routine generates VDBE code that causes the deletion of all +** index entries associated with a single row of a single table. +** +** The VDBE must be in a particular state when this routine is called. +** These are the requirements: +** +** 1. A read/write cursor pointing to pTab, the table containing the row +** to be deleted, must be opened as cursor number "iCur". +** +** 2. Read/write cursors for all indices of pTab must be open as +** cursor number iCur+i for the i-th index. +** +** 3. The "iCur" cursor must be pointing to the row that is to be +** deleted. +*/ +void sqlite3GenerateRowIndexDelete( + sqlite3 *db, /* The database containing the index */ + Vdbe *v, /* Generate code into this VDBE */ + Table *pTab, /* Table containing the row to be deleted */ + int iCur, /* Cursor number for the table */ + char *aIdxUsed /* Only delete if aIdxUsed!=0 && aIdxUsed[i]!=0 */ +){ + int i; + Index *pIdx; + + for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){ + if( aIdxUsed!=0 && aIdxUsed[i-1]==0 ) continue; + sqlite3GenerateIndexKey(v, pIdx, iCur); + sqlite3VdbeAddOp(v, OP_IdxDelete, iCur+i, 0); + } +} + +/* +** Generate code that will assemble an index key and put it on the top +** of the tack. The key with be for index pIdx which is an index on pTab. +** iCur is the index of a cursor open on the pTab table and pointing to +** the entry that needs indexing. +*/ +void sqlite3GenerateIndexKey( + Vdbe *v, /* Generate code into this VDBE */ + Index *pIdx, /* The index for which to generate a key */ + int iCur /* Cursor number for the pIdx->pTable table */ +){ + int j; + Table *pTab = pIdx->pTable; + + sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0); + for(j=0; j<pIdx->nColumn; j++){ + int idx = pIdx->aiColumn[j]; + if( idx==pTab->iPKey ){ + sqlite3VdbeAddOp(v, OP_Dup, j, 0); + }else{ + sqlite3VdbeAddOp(v, OP_Column, iCur, idx); + sqlite3ColumnDefault(v, pTab, idx); + } + } + sqlite3VdbeAddOp(v, OP_MakeRecord, pIdx->nColumn, (1<<24)); + sqlite3IndexAffinityStr(v, pIdx); +} |