394 lines
13 KiB
C
Executable File
394 lines
13 KiB
C
Executable File
/*
|
|
** 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,v 1.1.1.1 2004-03-11 22:22:23 alex 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 *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);
|
|
}
|
|
}
|