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lightning-sunbird  0.9+nobinonly
Functions
delete.c File Reference
#include "sqliteInt.h"

Go to the source code of this file.

Functions

Tablesqlite3SrcListLookup (Parse *pParse, SrcList *pSrc)
int sqlite3IsReadOnly (Parse *pParse, Table *pTab, int viewOk)
void sqlite3OpenTable (Parse *p, int iCur, int iDb, Table *pTab, int opcode)
void sqlite3DeleteFrom (Parse *pParse, SrcList *pTabList, Expr *pWhere)
void sqlite3GenerateRowDelete (sqlite3 *db, Vdbe *v, Table *pTab, int iCur, int count)
void sqlite3GenerateRowIndexDelete (Vdbe *v, Table *pTab, int iCur, char *aIdxUsed)
void sqlite3GenerateIndexKey (Vdbe *v, Index *pIdx, int iCur)

Function Documentation

void sqlite3DeleteFrom ( Parse pParse,
SrcList pTabList,
Expr pWhere 
)

Definition at line 86 of file delete.c.

 {
  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;

#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 || sqlite3MallocFailed() ){
    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;
  }
  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( 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, iDb);

  /* If we are trying to delete from a view, realize that view into
  ** a ephemeral table.
  */
  if( isView ){
    Select *pView = sqlite3SelectDup(pTab->pSelect);
    sqlite3Select(pParse, pView, SRT_VirtualTab, 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 addr2;
      if( !isView ){
        sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenRead);
      }
      sqlite3VdbeAddOp(v, OP_Rewind, iCur, sqlite3VdbeCurrentAddr(v)+2);
      addr2 = sqlite3VdbeAddOp(v, OP_AddImm, 1, 0);
      sqlite3VdbeAddOp(v, OP_Next, iCur, addr2);
      sqlite3VdbeResolveLabel(v, endOfLoop);
      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, OP_Rowid, iCur, 0);
    sqlite3VdbeAddOp(v, OP_FifoWrite, 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.
    */
    end = sqlite3VdbeMakeLabel(v);

    /* This is the beginning of the delete loop when there are
    ** row triggers.
    */
    if( triggers_exist ){
      addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, end);
      if( !isView ){
        sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
        sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenRead);
      }
      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_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);
      }

      /* 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);

    /* 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, COLNAME_NAME, "rows deleted", P3_STATIC);
  }

delete_from_cleanup:
  sqlite3AuthContextPop(&sContext);
  sqlite3SrcListDelete(pTabList);
  sqlite3ExprDelete(pWhere);
  return;
}

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void sqlite3GenerateIndexKey ( Vdbe v,
Index pIdx,
int  iCur 
)

Definition at line 431 of file delete.c.

 {
  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);
}

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void sqlite3GenerateRowDelete ( sqlite3 db,
Vdbe v,
Table pTab,
int  iCur,
int  count 
)

Definition at line 376 of file delete.c.

 {
  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);
}

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void sqlite3GenerateRowIndexDelete ( Vdbe v,
Table pTab,
int  iCur,
char *  aIdxUsed 
)

Definition at line 409 of file delete.c.

 {
  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);
  }
}

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int sqlite3IsReadOnly ( Parse pParse,
Table pTab,
int  viewOk 
)

Definition at line 44 of file delete.c.

                                                             {
  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;
}

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void sqlite3OpenTable ( Parse p,
int  iCur,
int  iDb,
Table pTab,
int  opcode 
)

Definition at line 62 of file delete.c.

 {
  Vdbe *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);
}

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Table* sqlite3SrcListLookup ( Parse pParse,
SrcList pSrc 
)

Definition at line 24 of file delete.c.

                                                         {
  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;
}

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