diff options
Diffstat (limited to 'src/libs/sqlite2/delete.c')
| -rw-r--r-- | src/libs/sqlite2/delete.c | 393 |
1 files changed, 393 insertions, 0 deletions
diff --git a/src/libs/sqlite2/delete.c b/src/libs/sqlite2/delete.c new file mode 100644 index 00000000..51054628 --- /dev/null +++ b/src/libs/sqlite2/delete.c @@ -0,0 +1,393 @@ +/* +** 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 DELETE FROM statements. +** +** $Id: delete.c 326789 2004-07-07 21:25:56Z pahlibar $ +*/ +#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 *sqliteSrcListLookup(Parse *pParse, SrcList *pSrc){ + Table *pTab = 0; + int i; + for(i=0; i<pSrc->nSrc; i++){ + const char *zTab = pSrc->a[i].zName; + const char *zDb = pSrc->a[i].zDatabase; + pTab = sqliteLocateTable(pParse, zTab, zDb); + pSrc->a[i].pTab = pTab; + } + 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 sqliteIsReadOnly(Parse *pParse, Table *pTab, int viewOk){ + if( pTab->readOnly ){ + sqliteErrorMsg(pParse, "table %s may not be modified", pTab->zName); + return 1; + } + if( !viewOk && pTab->pSelect ){ + sqliteErrorMsg(pParse, "cannot modify %s because it is a view",pTab->zName); + return 1; + } + return 0; +} + +/* +** Process a DELETE FROM statement. +*/ +void sqliteDeleteFrom( + 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; /* 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 */ + sqlite *db; /* Main database structure */ + int isView; /* True if attempting to delete from a view */ + AuthContext sContext; /* Authorization context */ + + int row_triggers_exist = 0; /* True if any triggers exist */ + int before_triggers; /* True if there are BEFORE triggers */ + int after_triggers; /* True if there are AFTER triggers */ + int oldIdx = -1; /* Cursor for the OLD table of AFTER triggers */ + + sContext.pParse = 0; + if( pParse->nErr || sqlite_malloc_failed ){ + pTabList = 0; + 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 = sqliteSrcListLookup(pParse, pTabList); + if( pTab==0 ) goto delete_from_cleanup; + before_triggers = sqliteTriggersExist(pParse, pTab->pTrigger, + TK_DELETE, TK_BEFORE, TK_ROW, 0); + after_triggers = sqliteTriggersExist(pParse, pTab->pTrigger, + TK_DELETE, TK_AFTER, TK_ROW, 0); + row_triggers_exist = before_triggers || after_triggers; + isView = pTab->pSelect!=0; + if( sqliteIsReadOnly(pParse, pTab, before_triggers) ){ + goto delete_from_cleanup; + } + assert( pTab->iDb<db->nDb ); + zDb = db->aDb[pTab->iDb].zName; + if( sqliteAuthCheck(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 && sqliteViewGetColumnNames(pParse, pTab) ){ + goto delete_from_cleanup; + } + + /* Allocate a cursor used to store the old.* data for a trigger. + */ + if( row_triggers_exist ){ + oldIdx = pParse->nTab++; + } + + /* Resolve the column names in all the expressions. + */ + assert( pTabList->nSrc==1 ); + iCur = pTabList->a[0].iCursor = pParse->nTab++; + if( pWhere ){ + if( sqliteExprResolveIds(pParse, pTabList, 0, pWhere) ){ + goto delete_from_cleanup; + } + if( sqliteExprCheck(pParse, pWhere, 0, 0) ){ + goto delete_from_cleanup; + } + } + + /* Start the view context + */ + if( isView ){ + sqliteAuthContextPush(pParse, &sContext, pTab->zName); + } + + /* Begin generating code. + */ + v = sqliteGetVdbe(pParse); + if( v==0 ){ + goto delete_from_cleanup; + } + sqliteBeginWriteOperation(pParse, row_triggers_exist, pTab->iDb); + + /* If we are trying to delete from a view, construct that view into + ** a temporary table. + */ + if( isView ){ + Select *pView = sqliteSelectDup(pTab->pSelect); + sqliteSelect(pParse, pView, SRT_TempTable, iCur, 0, 0, 0); + sqliteSelectDelete(pView); + } + + /* Initialize the counter of the number of rows deleted, if + ** we are counting rows. + */ + if( db->flags & SQLITE_CountRows ){ + sqliteVdbeAddOp(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 && !row_triggers_exist ){ + if( db->flags & SQLITE_CountRows ){ + /* If counting rows deleted, just count the total number of + ** entries in the table. */ + int endOfLoop = sqliteVdbeMakeLabel(v); + int addr; + if( !isView ){ + sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0); + sqliteVdbeAddOp(v, OP_OpenRead, iCur, pTab->tnum); + } + sqliteVdbeAddOp(v, OP_Rewind, iCur, sqliteVdbeCurrentAddr(v)+2); + addr = sqliteVdbeAddOp(v, OP_AddImm, 1, 0); + sqliteVdbeAddOp(v, OP_Next, iCur, addr); + sqliteVdbeResolveLabel(v, endOfLoop); + sqliteVdbeAddOp(v, OP_Close, iCur, 0); + } + if( !isView ){ + sqliteVdbeAddOp(v, OP_Clear, pTab->tnum, pTab->iDb); + for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ + sqliteVdbeAddOp(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{ + /* Begin the database scan + */ + pWInfo = sqliteWhereBegin(pParse, pTabList, pWhere, 1, 0); + if( pWInfo==0 ) goto delete_from_cleanup; + + /* Remember the key of every item to be deleted. + */ + sqliteVdbeAddOp(v, OP_ListWrite, 0, 0); + if( db->flags & SQLITE_CountRows ){ + sqliteVdbeAddOp(v, OP_AddImm, 1, 0); + } + + /* End the database scan loop. + */ + sqliteWhereEnd(pWInfo); + + /* Open the pseudo-table used to store OLD if there are triggers. + */ + if( row_triggers_exist ){ + sqliteVdbeAddOp(v, OP_OpenPseudo, oldIdx, 0); + } + + /* 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. + */ + sqliteVdbeAddOp(v, OP_ListRewind, 0, 0); + end = sqliteVdbeMakeLabel(v); + + /* This is the beginning of the delete loop when there are + ** row triggers. + */ + if( row_triggers_exist ){ + addr = sqliteVdbeAddOp(v, OP_ListRead, 0, end); + sqliteVdbeAddOp(v, OP_Dup, 0, 0); + if( !isView ){ + sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0); + sqliteVdbeAddOp(v, OP_OpenRead, iCur, pTab->tnum); + } + sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0); + + sqliteVdbeAddOp(v, OP_Recno, iCur, 0); + sqliteVdbeAddOp(v, OP_RowData, iCur, 0); + sqliteVdbeAddOp(v, OP_PutIntKey, oldIdx, 0); + if( !isView ){ + sqliteVdbeAddOp(v, OP_Close, iCur, 0); + } + + sqliteCodeRowTrigger(pParse, TK_DELETE, 0, TK_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. + */ + pParse->nTab = iCur + 1; + sqliteOpenTableAndIndices(pParse, pTab, iCur); + + /* This is the beginning of the delete loop when there are no + ** row triggers */ + if( !row_triggers_exist ){ + addr = sqliteVdbeAddOp(v, OP_ListRead, 0, end); + } + + /* Delete the row */ + sqliteGenerateRowDelete(db, v, pTab, iCur, pParse->trigStack==0); + } + + /* If there are row triggers, close all cursors then invoke + ** the AFTER triggers + */ + if( row_triggers_exist ){ + if( !isView ){ + for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){ + sqliteVdbeAddOp(v, OP_Close, iCur + i, pIdx->tnum); + } + sqliteVdbeAddOp(v, OP_Close, iCur, 0); + } + sqliteCodeRowTrigger(pParse, TK_DELETE, 0, TK_AFTER, pTab, -1, + oldIdx, (pParse->trigStack)?pParse->trigStack->orconf:OE_Default, + addr); + } + + /* End of the delete loop */ + sqliteVdbeAddOp(v, OP_Goto, 0, addr); + sqliteVdbeResolveLabel(v, end); + sqliteVdbeAddOp(v, OP_ListReset, 0, 0); + + /* Close the cursors after the loop if there are no row triggers */ + if( !row_triggers_exist ){ + for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){ + sqliteVdbeAddOp(v, OP_Close, iCur + i, pIdx->tnum); + } + sqliteVdbeAddOp(v, OP_Close, iCur, 0); + pParse->nTab = iCur; + } + } + sqliteVdbeAddOp(v, OP_SetCounts, 0, 0); + sqliteEndWriteOperation(pParse); + + /* + ** Return the number of rows that were deleted. + */ + if( db->flags & SQLITE_CountRows ){ + sqliteVdbeAddOp(v, OP_ColumnName, 0, 1); + sqliteVdbeChangeP3(v, -1, "rows deleted", P3_STATIC); + sqliteVdbeAddOp(v, OP_Callback, 1, 0); + } + +delete_from_cleanup: + sqliteAuthContextPop(&sContext); + sqliteSrcListDelete(pTabList); + sqliteExprDelete(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 sqliteGenerateRowDelete( + sqlite *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 = sqliteVdbeAddOp(v, OP_NotExists, iCur, 0); + sqliteGenerateRowIndexDelete(db, v, pTab, iCur, 0); + sqliteVdbeAddOp(v, OP_Delete, iCur, + (count?OPFLAG_NCHANGE:0) | OPFLAG_CSCHANGE); + sqliteVdbeChangeP2(v, addr, sqliteVdbeCurrentAddr(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 sqliteGenerateRowIndexDelete( + sqlite *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){ + int j; + if( aIdxUsed!=0 && aIdxUsed[i-1]==0 ) continue; + sqliteVdbeAddOp(v, OP_Recno, iCur, 0); + for(j=0; j<pIdx->nColumn; j++){ + int idx = pIdx->aiColumn[j]; + if( idx==pTab->iPKey ){ + sqliteVdbeAddOp(v, OP_Dup, j, 0); + }else{ + sqliteVdbeAddOp(v, OP_Column, iCur, idx); + } + } + sqliteVdbeAddOp(v, OP_MakeIdxKey, pIdx->nColumn, 0); + if( db->file_format>=4 ) sqliteAddIdxKeyType(v, pIdx); + sqliteVdbeAddOp(v, OP_IdxDelete, iCur+i, 0); + } +} |