--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/engine/sqlite/src/delete.cpp Thu Feb 25 14:29:19 2010 +0000
@@ -0,0 +1,471 @@
+/*
+** 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.cpp 1282 2008-11-13 09:31:33Z LarsPson $
+*/
+#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;
+ SrcList::SrcList_item *pItem;
+ for(i=0, pItem=pSrc->a; i<pSrc->nSrc; i++, pItem++){
+ pTab = sqlite3LocateTable(pParse, pItem->zName, pItem->zDatabase);
+ sqlite3DeleteTable(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)
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+ || (pTab->pMod && pTab->pMod->pModule->xUpdate==0)
+#endif
+ ){
+ 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 sqlite3OpenTable(
+ Parse *p, /* Generate code into this VDBE */
+ int iCur, /* The cursor number of the table */
+ int iDb, /* The database index in sqlite3.aDb[] */
+ Table *pTab, /* The table to be opened */
+ int opcode /* OP_OpenRead or OP_OpenWrite */
+){
+ Vdbe *v;
+ if( IsVirtual(pTab) ) return;
+ v = sqlite3GetVdbe(p);
+ assert( opcode==OP_OpenWrite || opcode==OP_OpenRead );
+ sqlite3TableLock(p, iDb, pTab->tnum, (opcode==OP_OpenWrite), pTab->zName);
+ sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
+ VdbeComment((v, "# %s", pTab->zName));
+ sqlite3VdbeAddOp(v, opcode, iCur, pTab->tnum);
+ 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 */
+ int iDb; /* Database number */
+ int memCnt = 0; /* Memory cell used for change counting */
+
+#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;
+ 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
+ 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;
+ }
+ iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
+ assert( iDb<db->nDb );
+ zDb = db->aDb[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( 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, iDb);
+
+ /* If we are trying to delete from a view, realize that view into
+ ** a ephemeral table.
+ */
+ if( isView ){
+ Select *pView = sqlite3SelectDup(db, pTab->pSelect);
+ sqlite3Select(pParse, pView, SRT_EphemTab, 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 ){
+ memCnt = pParse->nMem++;
+ sqlite3VdbeAddOp(v, OP_MemInt, 0, memCnt);
+ }
+
+ /* 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 && !IsVirtual(pTab) ){
+ if( db->flags & SQLITE_CountRows ){
+ /* If counting rows deleted, just count the total number of
+ ** entries in the table. */
+ int addr2;
+ if( !isView ){
+ sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenRead);
+ }
+ sqlite3VdbeAddOp(v, OP_Rewind, iCur, sqlite3VdbeCurrentAddr(v)+2);
+ addr2 = sqlite3VdbeAddOp(v, OP_MemIncr, 1, memCnt);
+ sqlite3VdbeAddOp(v, OP_Next, iCur, addr2);
+ sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
+ }
+ if( !isView ){
+ sqlite3VdbeAddOp(v, OP_Clear, pTab->tnum, iDb);
+ if( !pParse->nested ){
+ sqlite3VdbeChangeP3(v, -1, pTab->zName, P3_STATIC);
+ }
+ for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+ assert( pIdx->pSchema==pTab->pSchema );
+ sqlite3VdbeAddOp(v, OP_Clear, pIdx->tnum, 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 = sqlite3WhereBegin(pParse, pTabList, pWhere, 0);
+ if( pWInfo==0 ) goto delete_from_cleanup;
+
+ /* Remember the rowid of every item to be deleted.
+ */
+ sqlite3VdbeAddOp(v, IsVirtual(pTab) ? OP_VRowid : OP_Rowid, iCur, 0);
+ sqlite3VdbeAddOp(v, OP_FifoWrite, 0, 0);
+ if( db->flags & SQLITE_CountRows ){
+ sqlite3VdbeAddOp(v, OP_MemIncr, 1, memCnt);
+ }
+
+ /* 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.
+ */
+ end = sqlite3VdbeMakeLabel(v);
+
+ /* This is the beginning of the delete loop when there are
+ ** row triggers.
+ */
+ if( triggers_exist ){
+ int mem1 = pParse->nMem++;
+ addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, end);
+ sqlite3VdbeAddOp(v, OP_StackDepth, -1, 0);
+ sqlite3VdbeAddOp(v, OP_MemStore, mem1, 0);
+ if( !isView ){
+ sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenRead);
+ }
+ sqlite3VdbeAddOp(v, OP_NotExists, iCur, addr);
+ 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 ){
+ sqlite3VdbeAddOp(v, OP_MemLoad, mem1, 0);
+ }
+ }
+
+ 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_FifoRead 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_FifoRead, 0, end);
+ sqlite3VdbeAddOp(v, OP_StackDepth, -1, 0);
+ }
+
+ /* Delete the row */
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+ if( IsVirtual(pTab) ){
+ pParse->pVirtualLock = pTab;
+ sqlite3VdbeOp3(v, OP_VUpdate, 0, 1, (const char*)pTab->pVtab, P3_VTAB);
+ }else
+#endif
+ {
+ 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);
+
+ /* Close the cursors after the loop if there are no row triggers */
+ if( !triggers_exist && !IsVirtual(pTab) ){
+ 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_MemLoad, memCnt, 0);
+ sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
+ sqlite3VdbeSetNumCols(v, 1);
+ sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "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(v, pTab, iCur, 0);
+ sqlite3VdbeAddOp(v, OP_Delete, iCur, (count?OPFLAG_NCHANGE:0));
+ if( count ){
+ sqlite3VdbeChangeP3(v, -1, pTab->zName, P3_STATIC);
+ }
+ sqlite3VdbeJumpHere(v, addr);
+}
+
+/*
+** 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(
+ 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_MakeIdxRec, pIdx->nColumn, 0);
+ sqlite3IndexAffinityStr(v, pIdx);
+}