Ejemplo n.º 1
0
/*
** Generate code that will open cursors for a table and for all
** indices of that table.  The "base" parameter is the cursor number used
** for the table.  Indices are opened on subsequent cursors.
*/
void sqlite3OpenTableAndIndices(
  Parse *pParse,   /* Parsing context */
  Table *pTab,     /* Table to be opened */
  int base,        /* Cursor number assigned to the table */
  int op           /* OP_OpenRead or OP_OpenWrite */
){
  int i;
  int iDb;
  Index *pIdx;
  Vdbe *v;

  if( IsVirtual(pTab) ) return;
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
  v = sqlite3GetVdbe(pParse);
  assert( v!=0 );
  sqlite3OpenTable(pParse, base, iDb, pTab, op);
  for(i=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
    KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
    assert( pIdx->pSchema==pTab->pSchema );
    sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
    VdbeComment((v, "# %s", pIdx->zName));
    sqlite3VdbeOp3(v, op, i+base, pIdx->tnum, (char*)pKey, P3_KEYINFO_HANDOFF);
  }
  if( pParse->nTab<=base+i ){
    pParse->nTab = base+i;
  }
}
Ejemplo n.º 2
0
/*
 ** Allocate and return a pointer to a new sqlite3_value object. If
 ** the second argument to this function is NULL, the object is allocated
 ** by calling sqlite3ValueNew().
 **
 ** Otherwise, if the second argument is non-zero, then this function is
 ** being called indirectly by sqlite3Stat4ProbeSetValue(). If it has not
 ** already been allocated, allocate the UnpackedRecord structure that
 ** that function will return to its caller here. Then return a pointer
 ** an sqlite3_value within the UnpackedRecord.a[] array.
 */
static sqlite3_value *valueNew(sqlite3 *db, struct ValueNewStat4Ctx *p){
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
    if( p ){
        UnpackedRecord *pRec = p->ppRec[0];
        
        if( pRec==0 ){
            Index *pIdx = p->pIdx;      /* Index being probed */
            int nByte;                  /* Bytes of space to allocate */
            int i;                      /* Counter variable */
            int nCol = pIdx->nColumn+1; /* Number of index columns including rowid */
            
            nByte = sizeof(Mem) * nCol + sizeof(UnpackedRecord);
            pRec = (UnpackedRecord*)sqlite3DbMallocZero(db, nByte);
            if( pRec ){
                pRec->pKeyInfo = sqlite3IndexKeyinfo(p->pParse, pIdx);
                if( pRec->pKeyInfo ){
                    assert( pRec->pKeyInfo->nField+1==nCol );
                    pRec->pKeyInfo->enc = ENC(db);
                    pRec->flags = UNPACKED_PREFIX_MATCH;
                    pRec->aMem = (Mem *)&pRec[1];
                    for(i=0; i<nCol; i++){
                        pRec->aMem[i].flags = MEM_Null;
                        pRec->aMem[i].type = SQLITE_NULL;
                        pRec->aMem[i].db = db;
                    }
                }else{
                    sqlite3DbFree(db, pRec);
                    pRec = 0;
                }
            }
            if( pRec==0 ) return 0;
            p->ppRec[0] = pRec;
        }
        
        pRec->nField = p->iVal+1;
        return &pRec->aMem[p->iVal];
    }
#else
    UNUSED_PARAMETER(p);
#endif /* defined(SQLITE_ENABLE_STAT3_OR_STAT4) */
    return sqlite3ValueNew(db);
}
Ejemplo n.º 3
0
void sqlite3Update(
  Parse *pParse,         
  SrcList *pTabList,     
  ExprList *pChanges,    
  Expr *pWhere,          
  int onError            
){
  int i, j;              
  Table *pTab;           
  int addr = 0;          
  WhereInfo *pWInfo;     
  Vdbe *v;               
  Index *pIdx;           
  int nIdx;              
  int iCur;              
  sqlite3 *db;           
  int *aRegIdx = 0;      
  int *aXRef = 0;        
  int chngRowid;         
  Expr *pRowidExpr = 0;  
  int openAll = 0;       
  AuthContext sContext;  
  NameContext sNC;       
  int iDb;               
  int okOnePass;         
  int hasFK;             

#ifndef SQLITE_OMIT_TRIGGER
  int isView;            
  Trigger *pTrigger;     
  int tmask;             
#endif
  int newmask;           

  
  int regRowCount = 0;   
  int regOldRowid;       
  int regNewRowid;       
  int regNew;
  int regOld = 0;
  int regRowSet = 0;     

  memset(&sContext, 0, sizeof(sContext));
  db = pParse->db;
  if( pParse->nErr || db->mallocFailed ){
    goto update_cleanup;
  }
  assert( pTabList->nSrc==1 );

  pTab = sqlite3SrcListLookup(pParse, pTabList);
  if( pTab==0 ) goto update_cleanup;
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);

#ifndef SQLITE_OMIT_TRIGGER
  pTrigger = sqlite3TriggersExist(pParse, pTab, TK_UPDATE, pChanges, &tmask);
  isView = pTab->pSelect!=0;
  assert( pTrigger || tmask==0 );
#else
# define pTrigger 0
# define isView 0
# define tmask 0
#endif
#ifdef SQLITE_OMIT_VIEW
# undef isView
# define isView 0
#endif

  if( sqlite3ViewGetColumnNames(pParse, pTab) ){
    goto update_cleanup;
  }
  if( sqlite3IsReadOnly(pParse, pTab, tmask) ){
    goto update_cleanup;
  }
  aXRef = sqlite3DbMallocRaw(db, sizeof(int) * pTab->nCol );
  if( aXRef==0 ) goto update_cleanup;
  for(i=0; i<pTab->nCol; i++) aXRef[i] = -1;

  pTabList->a[0].iCursor = iCur = pParse->nTab++;
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    pParse->nTab++;
  }

  
  memset(&sNC, 0, sizeof(sNC));
  sNC.pParse = pParse;
  sNC.pSrcList = pTabList;

  chngRowid = 0;
  for(i=0; i<pChanges->nExpr; i++){
    if( sqlite3ResolveExprNames(&sNC, pChanges->a[i].pExpr) ){
      goto update_cleanup;
    }
    for(j=0; j<pTab->nCol; j++){
      if( sqlite3StrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){
        if( j==pTab->iPKey ){
          chngRowid = 1;
          pRowidExpr = pChanges->a[i].pExpr;
        }
        aXRef[j] = i;
        break;
      }
    }
    if( j>=pTab->nCol ){
      if( sqlite3IsRowid(pChanges->a[i].zName) ){
        chngRowid = 1;
        pRowidExpr = pChanges->a[i].pExpr;
      }else{
        sqlite3ErrorMsg(pParse, "no such column: %s", pChanges->a[i].zName);
        pParse->checkSchema = 1;
        goto update_cleanup;
      }
    }
#ifndef SQLITE_OMIT_AUTHORIZATION
    {
      int rc;
      rc = sqlite3AuthCheck(pParse, SQLITE_UPDATE, pTab->zName,
                           pTab->aCol[j].zName, db->aDb[iDb].zName);
      if( rc==SQLITE_DENY ){
        goto update_cleanup;
      }else if( rc==SQLITE_IGNORE ){
        aXRef[j] = -1;
      }
    }
#endif
  }

  hasFK = sqlite3FkRequired(pParse, pTab, aXRef, chngRowid);

  for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){}
  if( nIdx>0 ){
    aRegIdx = sqlite3DbMallocRaw(db, sizeof(Index*) * nIdx );
    if( aRegIdx==0 ) goto update_cleanup;
  }
  for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
    int reg;
    if( chngRowid ){
      reg = ++pParse->nMem;
    }else{
      reg = 0;
      for(i=0; i<pIdx->nColumn; i++){
        if( aXRef[pIdx->aiColumn[i]]>=0 ){
          reg = ++pParse->nMem;
          break;
        }
      }
    }
    aRegIdx[j] = reg;
  }

  
  v = sqlite3GetVdbe(pParse);
  if( v==0 ) goto update_cleanup;
  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
  sqlite3BeginWriteOperation(pParse, 1, iDb);

#ifndef SQLITE_OMIT_VIRTUALTABLE
  
  if( IsVirtual(pTab) ){
    updateVirtualTable(pParse, pTabList, pTab, pChanges, pRowidExpr, aXRef,
                       pWhere);
    pWhere = 0;
    pTabList = 0;
    goto update_cleanup;
  }
#endif

  
  regOldRowid = regNewRowid = ++pParse->nMem;
  if( pTrigger || hasFK ){
    regOld = pParse->nMem + 1;
    pParse->nMem += pTab->nCol;
  }
  if( chngRowid || pTrigger || hasFK ){
    regNewRowid = ++pParse->nMem;
  }
  regNew = pParse->nMem + 1;
  pParse->nMem += pTab->nCol;

  
  if( isView ){
    sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
  }

#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
  if( isView ){
    sqlite3MaterializeView(pParse, pTab, pWhere, iCur);
  }
#endif

  if( sqlite3ResolveExprNames(&sNC, pWhere) ){
    goto update_cleanup;
  }

  sqlite3VdbeAddOp2(v, OP_Null, 0, regOldRowid);
  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere,0, WHERE_ONEPASS_DESIRED);
  if( pWInfo==0 ) goto update_cleanup;
  okOnePass = pWInfo->okOnePass;

  sqlite3VdbeAddOp2(v, OP_Rowid, iCur, regOldRowid);
  if( !okOnePass ){
    regRowSet = ++pParse->nMem;
    sqlite3VdbeAddOp2(v, OP_RowSetAdd, regRowSet, regOldRowid);
  }

  sqlite3WhereEnd(pWInfo);

  if( (db->flags & SQLITE_CountRows) && !pParse->pTriggerTab ){
    regRowCount = ++pParse->nMem;
    sqlite3VdbeAddOp2(v, OP_Integer, 0, regRowCount);
  }

  if( !isView ){
    if( !okOnePass ) sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenWrite); 
    if( onError==OE_Replace ){
      openAll = 1;
    }else{
      openAll = 0;
      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
        if( pIdx->onError==OE_Replace ){
          openAll = 1;
          break;
        }
      }
    }
    for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
      if( openAll || aRegIdx[i]>0 ){
        KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
        sqlite3VdbeAddOp4(v, OP_OpenWrite, iCur+i+1, pIdx->tnum, iDb,
                       (char*)pKey, P4_KEYINFO_HANDOFF);
        assert( pParse->nTab>iCur+i+1 );
      }
    }
  }

  
  if( okOnePass ){
    int a1 = sqlite3VdbeAddOp1(v, OP_NotNull, regOldRowid);
    addr = sqlite3VdbeAddOp0(v, OP_Goto);
    sqlite3VdbeJumpHere(v, a1);
  }else{
    addr = sqlite3VdbeAddOp3(v, OP_RowSetRead, regRowSet, 0, regOldRowid);
  }

  sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addr, regOldRowid);

  assert( chngRowid || pTrigger || hasFK || regOldRowid==regNewRowid );
  if( chngRowid ){
    sqlite3ExprCode(pParse, pRowidExpr, regNewRowid);
    sqlite3VdbeAddOp1(v, OP_MustBeInt, regNewRowid);
  }

  if( hasFK || pTrigger ){
    u32 oldmask = (hasFK ? sqlite3FkOldmask(pParse, pTab) : 0);
    oldmask |= sqlite3TriggerColmask(pParse, 
        pTrigger, pChanges, 0, TRIGGER_BEFORE|TRIGGER_AFTER, pTab, onError
    );
    for(i=0; i<pTab->nCol; i++){
      if( aXRef[i]<0 || oldmask==0xffffffff || (i<32 && (oldmask & (1<<i))) ){
        sqlite3ExprCodeGetColumnOfTable(v, pTab, iCur, i, regOld+i);
      }else{
        sqlite3VdbeAddOp2(v, OP_Null, 0, regOld+i);
      }
    }
    if( chngRowid==0 ){
      sqlite3VdbeAddOp2(v, OP_Copy, regOldRowid, regNewRowid);
    }
  }

  newmask = sqlite3TriggerColmask(
      pParse, pTrigger, pChanges, 1, TRIGGER_BEFORE, pTab, onError
  );
  for(i=0; i<pTab->nCol; i++){
    if( i==pTab->iPKey ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regNew+i);
    }else{
      j = aXRef[i];
      if( j>=0 ){
        sqlite3ExprCode(pParse, pChanges->a[j].pExpr, regNew+i);
      }else if( 0==(tmask&TRIGGER_BEFORE) || i>31 || (newmask&(1<<i)) ){
        testcase( i==31 );
        testcase( i==32 );
        sqlite3VdbeAddOp3(v, OP_Column, iCur, i, regNew+i);
        sqlite3ColumnDefault(v, pTab, i, regNew+i);
      }
    }
  }

  if( tmask&TRIGGER_BEFORE ){
    sqlite3VdbeAddOp2(v, OP_Affinity, regNew, pTab->nCol);
    sqlite3TableAffinityStr(v, pTab);
    sqlite3CodeRowTrigger(pParse, pTrigger, TK_UPDATE, pChanges, 
        TRIGGER_BEFORE, pTab, regOldRowid, onError, addr);

    sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addr, regOldRowid);

    for(i=0; i<pTab->nCol; i++){
      if( aXRef[i]<0 && i!=pTab->iPKey ){
        sqlite3VdbeAddOp3(v, OP_Column, iCur, i, regNew+i);
        sqlite3ColumnDefault(v, pTab, i, regNew+i);
      }
    }
  }

  if( !isView ){
    int j1;                       

    
    sqlite3GenerateConstraintChecks(pParse, pTab, iCur, regNewRowid,
        aRegIdx, (chngRowid?regOldRowid:0), 1, onError, addr, 0);

    
    if( hasFK ){
      sqlite3FkCheck(pParse, pTab, regOldRowid, 0);
    }

    
    j1 = sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, regOldRowid);
    sqlite3GenerateRowIndexDelete(pParse, pTab, iCur, aRegIdx);
  
    
    if( hasFK || chngRowid ){
      sqlite3VdbeAddOp2(v, OP_Delete, iCur, 0);
    }
    sqlite3VdbeJumpHere(v, j1);

    if( hasFK ){
      sqlite3FkCheck(pParse, pTab, 0, regNewRowid);
    }
  
    
    sqlite3CompleteInsertion(pParse, pTab, iCur, regNewRowid, aRegIdx, 1, 0, 0);

 
    if( hasFK ){
      sqlite3FkActions(pParse, pTab, pChanges, regOldRowid);
    }
  }

  if( (db->flags & SQLITE_CountRows) && !pParse->pTriggerTab){
    sqlite3VdbeAddOp2(v, OP_AddImm, regRowCount, 1);
  }

  sqlite3CodeRowTrigger(pParse, pTrigger, TK_UPDATE, pChanges, 
      TRIGGER_AFTER, pTab, regOldRowid, onError, addr);

  sqlite3VdbeAddOp2(v, OP_Goto, 0, addr);
  sqlite3VdbeJumpHere(v, addr);

  
  for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
    if( openAll || aRegIdx[i]>0 ){
      sqlite3VdbeAddOp2(v, OP_Close, iCur+i+1, 0);
    }
  }
  sqlite3VdbeAddOp2(v, OP_Close, iCur, 0);

  if( pParse->nested==0 && pParse->pTriggerTab==0 ){
    sqlite3AutoincrementEnd(pParse);
  }

  if( (db->flags&SQLITE_CountRows) && !pParse->pTriggerTab && !pParse->nested ){
    sqlite3VdbeAddOp2(v, OP_ResultRow, regRowCount, 1);
    sqlite3VdbeSetNumCols(v, 1);
    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows updated", SQLITE_STATIC);
  }

update_cleanup:
  sqlite3AuthContextPop(&sContext);
  sqlite3DbFree(db, aRegIdx);
  sqlite3DbFree(db, aXRef);
  sqlite3SrcListDelete(db, pTabList);
  sqlite3ExprListDelete(db, pChanges);
  sqlite3ExprDelete(db, pWhere);
  return;
}
Ejemplo n.º 4
0
/*
** Process an UPDATE statement.
**
**   UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL;
**          \_______/ \________/     \______/       \________________/
*            onError   pTabList      pChanges             pWhere
*/
void sqlite3Update(
  Parse *pParse,         /* The parser context */
  SrcList *pTabList,     /* The table in which we should change things */
  ExprList *pChanges,    /* Things to be changed */
  Expr *pWhere,          /* The WHERE clause.  May be null */
  int onError            /* How to handle constraint errors */
){
  int i, j;              /* Loop counters */
  Table *pTab;           /* The table to be updated */
  int addr = 0;          /* VDBE instruction address of the start of the loop */
  WhereInfo *pWInfo;     /* Information about the WHERE clause */
  Vdbe *v;               /* The virtual database engine */
  Index *pIdx;           /* For looping over indices */
  int nIdx;              /* Number of indices that need updating */
  int iCur;              /* VDBE Cursor number of pTab */
  sqlite3 *db;           /* The database structure */
  int *aRegIdx = 0;      /* One register assigned to each index to be updated */
  int *aXRef = 0;        /* aXRef[i] is the index in pChanges->a[] of the
                         ** an expression for the i-th column of the table.
                         ** aXRef[i]==-1 if the i-th column is not changed. */
  int chngRowid;         /* True if the record number is being changed */
  Expr *pRowidExpr = 0;  /* Expression defining the new record number */
  int openAll = 0;       /* True if all indices need to be opened */
  AuthContext sContext;  /* The authorization context */
  NameContext sNC;       /* The name-context to resolve expressions in */
  int iDb;               /* Database containing the table being updated */
  int okOnePass;         /* True for one-pass algorithm without the FIFO */
  int hasFK;             /* True if foreign key processing is required */

#ifndef SQLITE_OMIT_TRIGGER
  int isView;            /* True when updating a view (INSTEAD OF trigger) */
  Trigger *pTrigger;     /* List of triggers on pTab, if required */
  int tmask;             /* Mask of TRIGGER_BEFORE|TRIGGER_AFTER */
#endif
  int newmask;           /* Mask of NEW.* columns accessed by BEFORE triggers */

  /* Register Allocations */
  int regRowCount = 0;   /* A count of rows changed */
  int regOldRowid;       /* The old rowid */
  int regNewRowid;       /* The new rowid */
  int regNew;
  int regOld = 0;
  int regRowSet = 0;     /* Rowset of rows to be updated */
  int regRec;            /* Register used for new table record to insert */

  memset(&sContext, 0, sizeof(sContext));
  db = pParse->db;
  if( pParse->nErr || db->mallocFailed ){
    goto update_cleanup;
  }
  assert( pTabList->nSrc==1 );

  /* Locate the table which we want to update. 
  */
  pTab = sqlite3SrcListLookup(pParse, pTabList);
  if( pTab==0 ) goto update_cleanup;
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);

  /* Figure out if we have any triggers and if the table being
  ** updated is a view.
  */
#ifndef SQLITE_OMIT_TRIGGER
  pTrigger = sqlite3TriggersExist(pParse, pTab, TK_UPDATE, pChanges, &tmask);
  isView = pTab->pSelect!=0;
  assert( pTrigger || tmask==0 );
#else
# define pTrigger 0
# define isView 0
# define tmask 0
#endif
#ifdef SQLITE_OMIT_VIEW
# undef isView
# define isView 0
#endif

  if( sqlite3ViewGetColumnNames(pParse, pTab) ){
    goto update_cleanup;
  }
  if( sqlite3IsReadOnly(pParse, pTab, tmask) ){
    goto update_cleanup;
  }
  aXRef = sqlite3DbMallocRaw(db, sizeof(int) * pTab->nCol );
  if( aXRef==0 ) goto update_cleanup;
  for(i=0; i<pTab->nCol; i++) aXRef[i] = -1;

  /* Allocate a cursors for the main database table and for all indices.
  ** The index cursors might not be used, but if they are used they
  ** need to occur right after the database cursor.  So go ahead and
  ** allocate enough space, just in case.
  */
  pTabList->a[0].iCursor = iCur = pParse->nTab++;
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    pParse->nTab++;
  }

  /* Initialize the name-context */
  memset(&sNC, 0, sizeof(sNC));
  sNC.pParse = pParse;
  sNC.pSrcList = pTabList;

  /* Resolve the column names in all the expressions of the
  ** of the UPDATE statement.  Also find the column index
  ** for each column to be updated in the pChanges array.  For each
  ** column to be updated, make sure we have authorization to change
  ** that column.
  */
  chngRowid = 0;
  for(i=0; i<pChanges->nExpr; i++){
    if( sqlite3ResolveExprNames(&sNC, pChanges->a[i].pExpr) ){
      goto update_cleanup;
    }
    for(j=0; j<pTab->nCol; j++){
      if( sqlite3StrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){
        if( j==pTab->iPKey ){
          chngRowid = 1;
          pRowidExpr = pChanges->a[i].pExpr;
        }
        aXRef[j] = i;
        break;
      }
    }
    if( j>=pTab->nCol ){
      if( sqlite3IsRowid(pChanges->a[i].zName) ){
        chngRowid = 1;
        pRowidExpr = pChanges->a[i].pExpr;
      }else{
        sqlite3ErrorMsg(pParse, "no such column: %s", pChanges->a[i].zName);
        pParse->checkSchema = 1;
        goto update_cleanup;
      }
    }
#ifndef SQLITE_OMIT_AUTHORIZATION
    {
      int rc;
      rc = sqlite3AuthCheck(pParse, SQLITE_UPDATE, pTab->zName,
                           pTab->aCol[j].zName, db->aDb[iDb].zName);
      if( rc==SQLITE_DENY ){
        goto update_cleanup;
      }else if( rc==SQLITE_IGNORE ){
        aXRef[j] = -1;
      }
    }
#endif
  }

  hasFK = sqlite3FkRequired(pParse, pTab, aXRef, chngRowid);

  /* Allocate memory for the array aRegIdx[].  There is one entry in the
  ** array for each index associated with table being updated.  Fill in
  ** the value with a register number for indices that are to be used
  ** and with zero for unused indices.
  */
  for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){}
  if( nIdx>0 ){
    aRegIdx = sqlite3DbMallocRaw(db, sizeof(Index*) * nIdx );
    if( aRegIdx==0 ) goto update_cleanup;
  }
  for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
    int reg;
    if( chngRowid ){
      reg = ++pParse->nMem;
    }else{
      reg = 0;
      for(i=0; i<pIdx->nColumn; i++){
        if( aXRef[pIdx->aiColumn[i]]>=0 ){
          reg = ++pParse->nMem;
          break;
        }
      }
    }
    aRegIdx[j] = reg;
  }

  /* Begin generating code. */
  v = sqlite3GetVdbe(pParse);
  if( v==0 ) goto update_cleanup;
  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
  sqlite3BeginWriteOperation(pParse, 1, iDb);

#ifndef SQLITE_OMIT_VIRTUALTABLE
  /* Virtual tables must be handled separately */
  if( IsVirtual(pTab) ){
    updateVirtualTable(pParse, pTabList, pTab, pChanges, pRowidExpr, aXRef,
                       pWhere);
    pWhere = 0;
    pTabList = 0;
    goto update_cleanup;
  }
#endif

  /* Allocate required registers. */
  regOldRowid = regNewRowid = ++pParse->nMem;
  if( pTrigger || hasFK ){
    regOld = pParse->nMem + 1;
    pParse->nMem += pTab->nCol;
  }
  if( chngRowid || pTrigger || hasFK ){
    regNewRowid = ++pParse->nMem;
  }
  regNew = pParse->nMem + 1;
  pParse->nMem += pTab->nCol;
  regRec = ++pParse->nMem;

  /* Start the view context. */
  if( isView ){
    sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
  }

  /* If we are trying to update a view, realize that view into
  ** a ephemeral table.
  */
#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
  if( isView ){
    sqlite3MaterializeView(pParse, pTab, pWhere, iCur);
  }
#endif

  /* Resolve the column names in all the expressions in the
  ** WHERE clause.
  */
  if( sqlite3ResolveExprNames(&sNC, pWhere) ){
    goto update_cleanup;
  }

  /* Begin the database scan
  */
  sqlite3VdbeAddOp2(v, OP_Null, 0, regOldRowid);
  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere,0, WHERE_ONEPASS_DESIRED);
  if( pWInfo==0 ) goto update_cleanup;
  okOnePass = pWInfo->okOnePass;

  /* Remember the rowid of every item to be updated.
  */
  sqlite3VdbeAddOp2(v, OP_Rowid, iCur, regOldRowid);
  if( !okOnePass ){
    regRowSet = ++pParse->nMem;
    sqlite3VdbeAddOp2(v, OP_RowSetAdd, regRowSet, regOldRowid);
  }

  /* End the database scan loop.
  */
  sqlite3WhereEnd(pWInfo);

  /* Initialize the count of updated rows
  */
  if( (db->flags & SQLITE_CountRows) && !pParse->pTriggerTab ){
    regRowCount = ++pParse->nMem;
    sqlite3VdbeAddOp2(v, OP_Integer, 0, regRowCount);
  }

  if( !isView ){
    /* 
    ** Open every index that needs updating.  Note that if any
    ** index could potentially invoke a REPLACE conflict resolution 
    ** action, then we need to open all indices because we might need
    ** to be deleting some records.
    */
    if( !okOnePass ) sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenWrite); 
    if( onError==OE_Replace ){
      openAll = 1;
    }else{
      openAll = 0;
      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
        if( pIdx->onError==OE_Replace ){
          openAll = 1;
          break;
        }
      }
    }
    for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
      if( openAll || aRegIdx[i]>0 ){
        KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
        sqlite3VdbeAddOp4(v, OP_OpenWrite, iCur+i+1, pIdx->tnum, iDb,
                       (char*)pKey, P4_KEYINFO_HANDOFF);
        assert( pParse->nTab>iCur+i+1 );
      }
    }
  }

  /* Top of the update loop */
  if( okOnePass ){
    int a1 = sqlite3VdbeAddOp1(v, OP_NotNull, regOldRowid);
    addr = sqlite3VdbeAddOp0(v, OP_Goto);
    sqlite3VdbeJumpHere(v, a1);
  }else{
    addr = sqlite3VdbeAddOp3(v, OP_RowSetRead, regRowSet, 0, regOldRowid);
  }

  /* Make cursor iCur point to the record that is being updated. If
  ** this record does not exist for some reason (deleted by a trigger,
  ** for example, then jump to the next iteration of the RowSet loop.  */
  sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addr, regOldRowid);

  /* If the record number will change, set register regNewRowid to
  ** contain the new value. If the record number is not being modified,
  ** then regNewRowid is the same register as regOldRowid, which is
  ** already populated.  */
  assert( chngRowid || pTrigger || hasFK || regOldRowid==regNewRowid );
  if( chngRowid ){
    sqlite3ExprCode(pParse, pRowidExpr, regNewRowid);
    sqlite3VdbeAddOp1(v, OP_MustBeInt, regNewRowid);
  }

  /* If there are triggers on this table, populate an array of registers 
  ** with the required old.* column data.  */
  if( hasFK || pTrigger ){
    u32 oldmask = (hasFK ? sqlite3FkOldmask(pParse, pTab) : 0);
    oldmask |= sqlite3TriggerColmask(pParse, 
        pTrigger, pChanges, 0, TRIGGER_BEFORE|TRIGGER_AFTER, pTab, onError
    );
    for(i=0; i<pTab->nCol; i++){
      if( aXRef[i]<0 || oldmask==0xffffffff || (oldmask & (1<<i)) ){
        sqlite3ExprCodeGetColumnOfTable(v, pTab, iCur, i, regOld+i);
      }else{
        sqlite3VdbeAddOp2(v, OP_Null, 0, regOld+i);
      }
    }
    if( chngRowid==0 ){
      sqlite3VdbeAddOp2(v, OP_Copy, regOldRowid, regNewRowid);
    }
  }

  /* Populate the array of registers beginning at regNew with the new
  ** row data. This array is used to check constaints, create the new
  ** table and index records, and as the values for any new.* references
  ** made by triggers.
  **
  ** If there are one or more BEFORE triggers, then do not populate the
  ** registers associated with columns that are (a) not modified by
  ** this UPDATE statement and (b) not accessed by new.* references. The
  ** values for registers not modified by the UPDATE must be reloaded from 
  ** the database after the BEFORE triggers are fired anyway (as the trigger 
  ** may have modified them). So not loading those that are not going to
  ** be used eliminates some redundant opcodes.
  */
  newmask = sqlite3TriggerColmask(
      pParse, pTrigger, pChanges, 1, TRIGGER_BEFORE, pTab, onError
  );
  for(i=0; i<pTab->nCol; i++){
    if( i==pTab->iPKey ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regNew+i);
    }else{
      j = aXRef[i];
      if( j>=0 ){
        sqlite3ExprCode(pParse, pChanges->a[j].pExpr, regNew+i);
      }else if( 0==(tmask&TRIGGER_BEFORE) || i>31 || (newmask&(1<<i)) ){
        /* This branch loads the value of a column that will not be changed 
        ** into a register. This is done if there are no BEFORE triggers, or
        ** if there are one or more BEFORE triggers that use this value via
        ** a new.* reference in a trigger program.
        */
        testcase( i==31 );
        testcase( i==32 );
        sqlite3VdbeAddOp3(v, OP_Column, iCur, i, regNew+i);
        sqlite3ColumnDefault(v, pTab, i, regNew+i);
      }
    }
  }

  /* Fire any BEFORE UPDATE triggers. This happens before constraints are
  ** verified. One could argue that this is wrong.
  */
  if( tmask&TRIGGER_BEFORE ){
    sqlite3VdbeAddOp2(v, OP_Affinity, regNew, pTab->nCol);
    sqlite3TableAffinityStr(v, pTab);
    sqlite3CodeRowTrigger(pParse, pTrigger, TK_UPDATE, pChanges, 
        TRIGGER_BEFORE, pTab, regOldRowid, onError, addr);

    /* The row-trigger may have deleted the row being updated. In this
    ** case, jump to the next row. No updates or AFTER triggers are 
    ** required. This behaviour - what happens when the row being updated
    ** is deleted or renamed by a BEFORE trigger - is left undefined in the
    ** documentation.
    */
    sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addr, regOldRowid);

    /* If it did not delete it, the row-trigger may still have modified 
    ** some of the columns of the row being updated. Load the values for 
    ** all columns not modified by the update statement into their 
    ** registers in case this has happened.
    */
    for(i=0; i<pTab->nCol; i++){
      if( aXRef[i]<0 && i!=pTab->iPKey ){
        sqlite3VdbeAddOp3(v, OP_Column, iCur, i, regNew+i);
        sqlite3ColumnDefault(v, pTab, i, regNew+i);
      }
    }
  }

  if( !isView ){
    int j1;                       /* Address of jump instruction */

    /* Do constraint checks. */
    sqlite3GenerateConstraintChecks(pParse, pTab, iCur, regNewRowid,
        aRegIdx, (chngRowid?regOldRowid:0), 1, onError, addr, 0);

    /* Do FK constraint checks. */
    if( hasFK ){
      sqlite3FkCheck(pParse, pTab, regOldRowid, 0);
    }

    /* Delete the index entries associated with the current record.  */
    j1 = sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, regOldRowid);
    sqlite3GenerateRowIndexDelete(pParse, pTab, iCur, aRegIdx);
  
    /* If changing the record number, delete the old record.  */
    if( hasFK || chngRowid ){
      sqlite3VdbeAddOp2(v, OP_Delete, iCur, 0);
    }
    sqlite3VdbeJumpHere(v, j1);

    if( hasFK ){
      sqlite3FkCheck(pParse, pTab, 0, regNewRowid);
    }
  
    /* Insert the new index entries and the new record. */
    sqlite3CompleteInsertion(pParse, pTab, iCur, regNewRowid, aRegIdx, 1, 0, 0);

    /* Do any ON CASCADE, SET NULL or SET DEFAULT operations required to
    ** handle rows (possibly in other tables) that refer via a foreign key
    ** to the row just updated. */ 
    if( hasFK ){
      sqlite3FkActions(pParse, pTab, pChanges, regOldRowid);
    }
  }

  /* Increment the row counter 
  */
  if( (db->flags & SQLITE_CountRows) && !pParse->pTriggerTab){
    sqlite3VdbeAddOp2(v, OP_AddImm, regRowCount, 1);
  }

  sqlite3CodeRowTrigger(pParse, pTrigger, TK_UPDATE, pChanges, 
      TRIGGER_AFTER, pTab, regOldRowid, onError, addr);

  /* Repeat the above with the next record to be updated, until
  ** all record selected by the WHERE clause have been updated.
  */
  sqlite3VdbeAddOp2(v, OP_Goto, 0, addr);
  sqlite3VdbeJumpHere(v, addr);

  /* Close all tables */
  for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
    if( openAll || aRegIdx[i]>0 ){
      sqlite3VdbeAddOp2(v, OP_Close, iCur+i+1, 0);
    }
  }
  sqlite3VdbeAddOp2(v, OP_Close, iCur, 0);

  /* Update the sqlite_sequence table by storing the content of the
  ** maximum rowid counter values recorded while inserting into
  ** autoincrement tables.
  */
  if( pParse->nested==0 && pParse->pTriggerTab==0 ){
    sqlite3AutoincrementEnd(pParse);
  }

  /*
  ** Return the number of rows that were changed. If this routine is 
  ** generating code because of a call to sqlite3NestedParse(), do not
  ** invoke the callback function.
  */
  if( (db->flags&SQLITE_CountRows) && !pParse->pTriggerTab && !pParse->nested ){
    sqlite3VdbeAddOp2(v, OP_ResultRow, regRowCount, 1);
    sqlite3VdbeSetNumCols(v, 1);
    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows updated", SQLITE_STATIC);
  }

update_cleanup:
  sqlite3AuthContextPop(&sContext);
  sqlite3DbFree(db, aRegIdx);
  sqlite3DbFree(db, aXRef);
  sqlite3SrcListDelete(db, pTabList);
  sqlite3ExprListDelete(db, pChanges);
  sqlite3ExprDelete(db, pWhere);
  return;
}
Ejemplo n.º 5
0
/*
** Process an UPDATE statement.
**
**   UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL;
**          \_______/ \________/     \______/       \________________/
*            onError   pTabList      pChanges             pWhere
*/
void sqlite3Update(
  Parse *pParse,         /* The parser context */
  SrcList *pTabList,     /* The table in which we should change things */
  ExprList *pChanges,    /* Things to be changed */
  Expr *pWhere,          /* The WHERE clause.  May be null */
  int onError            /* How to handle constraint errors */
){
  int i, j;              /* Loop counters */
  Table *pTab;           /* The table to be updated */
  int addr = 0;          /* VDBE instruction address of the start of the loop */
  WhereInfo *pWInfo;     /* Information about the WHERE clause */
  Vdbe *v;               /* The virtual database engine */
  Index *pIdx;           /* For looping over indices */
  int nIdx;              /* Number of indices that need updating */
  int iCur;              /* VDBE Cursor number of pTab */
  sqlite3 *db;           /* The database structure */
  int *aRegIdx = 0;      /* One register assigned to each index to be updated */
  int *aXRef = 0;        /* aXRef[i] is the index in pChanges->a[] of the
                         ** an expression for the i-th column of the table.
                         ** aXRef[i]==-1 if the i-th column is not changed. */
  int chngRowid;         /* True if the record number is being changed */
  Expr *pRowidExpr = 0;  /* Expression defining the new record number */
  int openAll = 0;       /* True if all indices need to be opened */
  AuthContext sContext;  /* The authorization context */
  NameContext sNC;       /* The name-context to resolve expressions in */
  int iDb;               /* Database containing the table being updated */
  int j1;                /* Addresses of jump instructions */
  int okOnePass;         /* True for one-pass algorithm without the FIFO */

#ifndef SQLITE_OMIT_TRIGGER
  int isView;                  /* Trying to update a view */
  int triggers_exist = 0;      /* True if any row triggers exist */
#endif
  int iBeginAfterTrigger = 0;  /* Address of after trigger program */
  int iEndAfterTrigger = 0;    /* Exit of after trigger program */
  int iBeginBeforeTrigger = 0; /* Address of before trigger program */
  int iEndBeforeTrigger = 0;   /* Exit of before trigger program */
  u32 old_col_mask = 0;        /* Mask of OLD.* columns in use */
  u32 new_col_mask = 0;        /* Mask of NEW.* columns in use */

  int newIdx      = -1;  /* index of trigger "new" temp table       */
  int oldIdx      = -1;  /* index of trigger "old" temp table       */

  /* Register Allocations */
  int regRowCount = 0;   /* A count of rows changed */
  int regOldRowid;       /* The old rowid */
  int regNewRowid;       /* The new rowid */
  int regData;           /* New data for the row */
  int regRowSet = 0;     /* Rowset of rows to be updated */

  sContext.pParse = 0;
  db = pParse->db;
  if( pParse->nErr || db->mallocFailed ){
    goto update_cleanup;
  }
  assert( pTabList->nSrc==1 );

  /* Locate the table which we want to update. 
  */
  pTab = sqlite3SrcListLookup(pParse, pTabList);
  if( pTab==0 ) goto update_cleanup;
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);

  /* Figure out if we have any triggers and if the table being
  ** updated is a view
  */
#ifndef SQLITE_OMIT_TRIGGER
  triggers_exist = sqlite3TriggersExist(pTab, TK_UPDATE, pChanges);
  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 update_cleanup;
  }
  if( sqlite3ViewGetColumnNames(pParse, pTab) ){
    goto update_cleanup;
  }
  aXRef = sqlite3DbMallocRaw(db, sizeof(int) * pTab->nCol );
  if( aXRef==0 ) goto update_cleanup;
  for(i=0; i<pTab->nCol; i++) aXRef[i] = -1;

  /* If there are FOR EACH ROW triggers, allocate cursors for the
  ** special OLD and NEW tables
  */
  if( triggers_exist ){
    newIdx = pParse->nTab++;
    oldIdx = pParse->nTab++;
  }

  /* Allocate a cursors for the main database table and for all indices.
  ** The index cursors might not be used, but if they are used they
  ** need to occur right after the database cursor.  So go ahead and
  ** allocate enough space, just in case.
  */
  pTabList->a[0].iCursor = iCur = pParse->nTab++;
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    pParse->nTab++;
  }

  /* Initialize the name-context */
  memset(&sNC, 0, sizeof(sNC));
  sNC.pParse = pParse;
  sNC.pSrcList = pTabList;

  /* Resolve the column names in all the expressions of the
  ** of the UPDATE statement.  Also find the column index
  ** for each column to be updated in the pChanges array.  For each
  ** column to be updated, make sure we have authorization to change
  ** that column.
  */
  chngRowid = 0;
  for(i=0; i<pChanges->nExpr; i++){
    if( sqlite3ResolveExprNames(&sNC, pChanges->a[i].pExpr) ){
      goto update_cleanup;
    }
    for(j=0; j<pTab->nCol; j++){
      if( sqlite3StrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){
        if( j==pTab->iPKey ){
          chngRowid = 1;
          pRowidExpr = pChanges->a[i].pExpr;
        }
        aXRef[j] = i;
        break;
      }
    }
    if( j>=pTab->nCol ){
      if( sqlite3IsRowid(pChanges->a[i].zName) ){
        chngRowid = 1;
        pRowidExpr = pChanges->a[i].pExpr;
      }else{
        sqlite3ErrorMsg(pParse, "no such column: %s", pChanges->a[i].zName);
        goto update_cleanup;
      }
    }
#ifndef SQLITE_OMIT_AUTHORIZATION
    {
      int rc;
      rc = sqlite3AuthCheck(pParse, SQLITE_UPDATE, pTab->zName,
                           pTab->aCol[j].zName, db->aDb[iDb].zName);
      if( rc==SQLITE_DENY ){
        goto update_cleanup;
      }else if( rc==SQLITE_IGNORE ){
        aXRef[j] = -1;
      }
    }
#endif
  }

  /* Allocate memory for the array aRegIdx[].  There is one entry in the
  ** array for each index associated with table being updated.  Fill in
  ** the value with a register number for indices that are to be used
  ** and with zero for unused indices.
  */
  for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){}
  if( nIdx>0 ){
    aRegIdx = sqlite3DbMallocRaw(db, sizeof(Index*) * nIdx );
    if( aRegIdx==0 ) goto update_cleanup;
  }
  for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
    int reg;
    if( chngRowid ){
      reg = ++pParse->nMem;
    }else{
      reg = 0;
      for(i=0; i<pIdx->nColumn; i++){
        if( aXRef[pIdx->aiColumn[i]]>=0 ){
          reg = ++pParse->nMem;
          break;
        }
      }
    }
    aRegIdx[j] = reg;
  }

  /* Allocate a block of register used to store the change record
  ** sent to sqlite3GenerateConstraintChecks().  There are either
  ** one or two registers for holding the rowid.  One rowid register
  ** is used if chngRowid is false and two are used if chngRowid is
  ** true.  Following these are pTab->nCol register holding column
  ** data.
  */
  regOldRowid = regNewRowid = pParse->nMem + 1;
  pParse->nMem += pTab->nCol + 1;
  if( chngRowid ){
    regNewRowid++;
    pParse->nMem++;
  }
  regData = regNewRowid+1;
 

  /* Begin generating code.
  */
  v = sqlite3GetVdbe(pParse);
  if( v==0 ) goto update_cleanup;
  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
  sqlite3BeginWriteOperation(pParse, 1, iDb);

#ifndef SQLITE_OMIT_VIRTUALTABLE
  /* Virtual tables must be handled separately */
  if( IsVirtual(pTab) ){
    updateVirtualTable(pParse, pTabList, pTab, pChanges, pRowidExpr, aXRef,
                       pWhere);
    pWhere = 0;
    pTabList = 0;
    goto update_cleanup;
  }
#endif

  /* Start the view context
  */
  if( isView ){
    sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
  }

  /* Generate the code for triggers.
  */
  if( triggers_exist ){
    int iGoto;

    /* Create pseudo-tables for NEW and OLD
    */
    sqlite3VdbeAddOp2(v, OP_SetNumColumns, 0, pTab->nCol);
    sqlite3VdbeAddOp2(v, OP_OpenPseudo, oldIdx, 0);
    sqlite3VdbeAddOp2(v, OP_SetNumColumns, 0, pTab->nCol);
    sqlite3VdbeAddOp2(v, OP_OpenPseudo, newIdx, 0);

    iGoto = sqlite3VdbeAddOp2(v, OP_Goto, 0, 0);
    addr = sqlite3VdbeMakeLabel(v);
    iBeginBeforeTrigger = sqlite3VdbeCurrentAddr(v);
    if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TRIGGER_BEFORE, pTab,
          newIdx, oldIdx, onError, addr, &old_col_mask, &new_col_mask) ){
      goto update_cleanup;
    }
    iEndBeforeTrigger = sqlite3VdbeAddOp2(v, OP_Goto, 0, 0);
    iBeginAfterTrigger = sqlite3VdbeCurrentAddr(v);
    if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TRIGGER_AFTER, pTab, 
          newIdx, oldIdx, onError, addr, &old_col_mask, &new_col_mask) ){
      goto update_cleanup;
    }
    iEndAfterTrigger = sqlite3VdbeAddOp2(v, OP_Goto, 0, 0);
    sqlite3VdbeJumpHere(v, iGoto);
  }

  /* If we are trying to update a view, realize that view into
  ** a ephemeral table.
  */
#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
  if( isView ){
    sqlite3MaterializeView(pParse, pTab, pWhere, iCur);
  }
#endif

  /* Resolve the column names in all the expressions in the
  ** WHERE clause.
  */
  if( sqlite3ResolveExprNames(&sNC, pWhere) ){
    goto update_cleanup;
  }

  /* Begin the database scan
  */
  sqlite3VdbeAddOp2(v, OP_Null, 0, regOldRowid);
  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0,
                             WHERE_ONEPASS_DESIRED, 0);
  if( pWInfo==0 ) goto update_cleanup;
  okOnePass = pWInfo->okOnePass;

  /* Remember the rowid of every item to be updated.
  */
  sqlite3VdbeAddOp2(v, IsVirtual(pTab)?OP_VRowid:OP_Rowid, iCur, regOldRowid);
  if( !okOnePass ){
    regRowSet = ++pParse->nMem;
    sqlite3VdbeAddOp2(v, OP_RowSetAdd, regRowSet, regOldRowid);
  }

  /* End the database scan loop.
  */
  sqlite3WhereEnd(pWInfo);

  /* Initialize the count of updated rows
  */
  if( db->flags & SQLITE_CountRows && !pParse->trigStack ){
    regRowCount = ++pParse->nMem;
    sqlite3VdbeAddOp2(v, OP_Integer, 0, regRowCount);
  }

  if( !isView && !IsVirtual(pTab) ){
    /* 
    ** Open every index that needs updating.  Note that if any
    ** index could potentially invoke a REPLACE conflict resolution 
    ** action, then we need to open all indices because we might need
    ** to be deleting some records.
    */
    if( !okOnePass ) sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenWrite); 
    if( onError==OE_Replace ){
      openAll = 1;
    }else{
      openAll = 0;
      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
        if( pIdx->onError==OE_Replace ){
          openAll = 1;
          break;
        }
      }
    }
    for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
      if( openAll || aRegIdx[i]>0 ){
        KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
        sqlite3VdbeAddOp4(v, OP_OpenWrite, iCur+i+1, pIdx->tnum, iDb,
                       (char*)pKey, P4_KEYINFO_HANDOFF);
        assert( pParse->nTab>iCur+i+1 );
      }
    }
  }
  
  /* Jump back to this point if a trigger encounters an IGNORE constraint. */
  if( triggers_exist ){
    sqlite3VdbeResolveLabel(v, addr);
  }

  /* Top of the update loop */
  if( okOnePass ){
    int a1 = sqlite3VdbeAddOp1(v, OP_NotNull, regOldRowid);
    addr = sqlite3VdbeAddOp0(v, OP_Goto);
    sqlite3VdbeJumpHere(v, a1);
  }else{
    addr = sqlite3VdbeAddOp3(v, OP_RowSetRead, regRowSet, 0, regOldRowid);
  }

  if( triggers_exist ){
    int regRowid;
    int regRow;
    int regCols;

    /* Make cursor iCur point to the record that is being updated.
    */
    sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addr, regOldRowid);

    /* Generate the OLD table
    */
    regRowid = sqlite3GetTempReg(pParse);
    regRow = sqlite3GetTempReg(pParse);
    sqlite3VdbeAddOp2(v, OP_Rowid, iCur, regRowid);
    if( !old_col_mask ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regRow);
    }else{
      sqlite3VdbeAddOp2(v, OP_RowData, iCur, regRow);
    }
    sqlite3VdbeAddOp3(v, OP_Insert, oldIdx, regRow, regRowid);

    /* Generate the NEW table
    */
    if( chngRowid ){
      sqlite3ExprCodeAndCache(pParse, pRowidExpr, regRowid);
      sqlite3VdbeAddOp1(v, OP_MustBeInt, regRowid);
    }else{
      sqlite3VdbeAddOp2(v, OP_Rowid, iCur, regRowid);
    }
    regCols = sqlite3GetTempRange(pParse, pTab->nCol);
    for(i=0; i<pTab->nCol; i++){
      if( i==pTab->iPKey ){
        sqlite3VdbeAddOp2(v, OP_Null, 0, regCols+i);
        continue;
      }
      j = aXRef[i];
      if( new_col_mask&((u32)1<<i) || new_col_mask==0xffffffff ){
        if( j<0 ){
          sqlite3VdbeAddOp3(v, OP_Column, iCur, i, regCols+i);
          sqlite3ColumnDefault(v, pTab, i);
        }else{
          sqlite3ExprCodeAndCache(pParse, pChanges->a[j].pExpr, regCols+i);
        }
      }else{
        sqlite3VdbeAddOp2(v, OP_Null, 0, regCols+i);
      }
    }
    sqlite3VdbeAddOp3(v, OP_MakeRecord, regCols, pTab->nCol, regRow);
    if( !isView ){
      sqlite3TableAffinityStr(v, pTab);
      sqlite3ExprCacheAffinityChange(pParse, regCols, pTab->nCol);
    }
    sqlite3ReleaseTempRange(pParse, regCols, pTab->nCol);
    /* if( pParse->nErr ) goto update_cleanup; */
    sqlite3VdbeAddOp3(v, OP_Insert, newIdx, regRow, regRowid);
    sqlite3ReleaseTempReg(pParse, regRowid);
    sqlite3ReleaseTempReg(pParse, regRow);

    sqlite3VdbeAddOp2(v, OP_Goto, 0, iBeginBeforeTrigger);
    sqlite3VdbeJumpHere(v, iEndBeforeTrigger);
  }

  if( !isView && !IsVirtual(pTab) ){
    /* Loop over every record that needs updating.  We have to load
    ** the old data for each record to be updated because some columns
    ** might not change and we will need to copy the old value.
    ** Also, the old data is needed to delete the old index entries.
    ** So make the cursor point at the old record.
    */
    sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addr, regOldRowid);

    /* If the record number will change, push the record number as it
    ** will be after the update. (The old record number is currently
    ** on top of the stack.)
    */
    if( chngRowid ){
      sqlite3ExprCode(pParse, pRowidExpr, regNewRowid);
      sqlite3VdbeAddOp1(v, OP_MustBeInt, regNewRowid);
    }

    /* Compute new data for this record.  
    */
    for(i=0; i<pTab->nCol; i++){
      if( i==pTab->iPKey ){
        sqlite3VdbeAddOp2(v, OP_Null, 0, regData+i);
        continue;
      }
      j = aXRef[i];
      if( j<0 ){
        sqlite3VdbeAddOp3(v, OP_Column, iCur, i, regData+i);
        sqlite3ColumnDefault(v, pTab, i);
      }else{
        sqlite3ExprCode(pParse, pChanges->a[j].pExpr, regData+i);
      }
    }

    /* Do constraint checks
    */
    sqlite3GenerateConstraintChecks(pParse, pTab, iCur, regNewRowid,
                                    aRegIdx, chngRowid, 1,
                                    onError, addr);

    /* Delete the old indices for the current record.
    */
    j1 = sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, regOldRowid);
    sqlite3GenerateRowIndexDelete(pParse, pTab, iCur, aRegIdx);

    /* If changing the record number, delete the old record.
    */
    if( chngRowid ){
      sqlite3VdbeAddOp2(v, OP_Delete, iCur, 0);
    }
    sqlite3VdbeJumpHere(v, j1);

    /* Create the new index entries and the new record.
    */
    sqlite3CompleteInsertion(pParse, pTab, iCur, regNewRowid, 
                             aRegIdx, 1, -1, 0);
  }

  /* Increment the row counter 
  */
  if( db->flags & SQLITE_CountRows && !pParse->trigStack){
    sqlite3VdbeAddOp2(v, OP_AddImm, regRowCount, 1);
  }

  /* If there are triggers, close all the cursors after each iteration
  ** through the loop.  The fire the after triggers.
  */
  if( triggers_exist ){
    sqlite3VdbeAddOp2(v, OP_Goto, 0, iBeginAfterTrigger);
    sqlite3VdbeJumpHere(v, iEndAfterTrigger);
  }

  /* Repeat the above with the next record to be updated, until
  ** all record selected by the WHERE clause have been updated.
  */
  sqlite3VdbeAddOp2(v, OP_Goto, 0, addr);
  sqlite3VdbeJumpHere(v, addr);

  /* Close all tables */
  for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
    if( openAll || aRegIdx[i]>0 ){
      sqlite3VdbeAddOp2(v, OP_Close, iCur+i+1, 0);
    }
  }
  sqlite3VdbeAddOp2(v, OP_Close, iCur, 0);
  if( triggers_exist ){
    sqlite3VdbeAddOp2(v, OP_Close, newIdx, 0);
    sqlite3VdbeAddOp2(v, OP_Close, oldIdx, 0);
  }

  /*
  ** Return the number of rows that were changed. If this routine is 
  ** generating code because of a call to sqlite3NestedParse(), do not
  ** invoke the callback function.
  */
  if( db->flags & SQLITE_CountRows && !pParse->trigStack && pParse->nested==0 ){
    sqlite3VdbeAddOp2(v, OP_ResultRow, regRowCount, 1);
    sqlite3VdbeSetNumCols(v, 1);
    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows updated", SQLITE_STATIC);
  }

update_cleanup:
  sqlite3AuthContextPop(&sContext);
  sqlite3DbFree(db, aRegIdx);
  sqlite3DbFree(db, aXRef);
  sqlite3SrcListDelete(db, pTabList);
  sqlite3ExprListDelete(db, pChanges);
  sqlite3ExprDelete(db, pWhere);
  return;
}
Ejemplo n.º 6
0
/*
** This function is called when a row is inserted into or deleted from the 
** child table of foreign key constraint pFKey. If an SQL UPDATE is executed 
** on the child table of pFKey, this function is invoked twice for each row
** affected - once to "delete" the old row, and then again to "insert" the
** new row.
**
** Each time it is called, this function generates VDBE code to locate the
** row in the parent table that corresponds to the row being inserted into 
** or deleted from the child table. If the parent row can be found, no 
** special action is taken. Otherwise, if the parent row can *not* be
** found in the parent table:
**
**   Operation | FK type   | Action taken
**   --------------------------------------------------------------------------
**   INSERT      immediate   Increment the "immediate constraint counter".
**
**   DELETE      immediate   Decrement the "immediate constraint counter".
**
**   INSERT      deferred    Increment the "deferred constraint counter".
**
**   DELETE      deferred    Decrement the "deferred constraint counter".
**
** These operations are identified in the comment at the top of this file 
** (fkey.c) as "I.1" and "D.1".
*/
static void fkLookupParent(
  Parse *pParse,        /* Parse context */
  int iDb,              /* Index of database housing pTab */
  Table *pTab,          /* Parent table of FK pFKey */
  Index *pIdx,          /* Unique index on parent key columns in pTab */
  FKey *pFKey,          /* Foreign key constraint */
  int *aiCol,           /* Map from parent key columns to child table columns */
  int regData,          /* Address of array containing child table row */
  int nIncr,            /* Increment constraint counter by this */
  int isIgnore          /* If true, pretend pTab contains all NULL values */
){
  int i;                                    /* Iterator variable */
  Vdbe *v = sqlite3GetVdbe(pParse);         /* Vdbe to add code to */
  int iCur = pParse->nTab - 1;              /* Cursor number to use */
  int iOk = sqlite3VdbeMakeLabel(v);        /* jump here if parent key found */

  /* If nIncr is less than zero, then check at runtime if there are any
  ** outstanding constraints to resolve. If there are not, there is no need
  ** to check if deleting this row resolves any outstanding violations.
  **
  ** Check if any of the key columns in the child table row are NULL. If 
  ** any are, then the constraint is considered satisfied. No need to 
  ** search for a matching row in the parent table.  */
  if( nIncr<0 ){
    sqlite3VdbeAddOp2(v, OP_FkIfZero, pFKey->isDeferred, iOk);
  }
  for(i=0; i<pFKey->nCol; i++){
    int iReg = aiCol[i] + regData + 1;
    sqlite3VdbeAddOp2(v, OP_IsNull, iReg, iOk);
  }

  if( isIgnore==0 ){
    if( pIdx==0 ){
      /* If pIdx is NULL, then the parent key is the INTEGER PRIMARY KEY
      ** column of the parent table (table pTab).  */
      int iMustBeInt;               /* Address of MustBeInt instruction */
      int regTemp = sqlite3GetTempReg(pParse);
  
      /* Invoke MustBeInt to coerce the child key value to an integer (i.e. 
      ** apply the affinity of the parent key). If this fails, then there
      ** is no matching parent key. Before using MustBeInt, make a copy of
      ** the value. Otherwise, the value inserted into the child key column
      ** will have INTEGER affinity applied to it, which may not be correct.  */
      sqlite3VdbeAddOp2(v, OP_SCopy, aiCol[0]+1+regData, regTemp);
      iMustBeInt = sqlite3VdbeAddOp2(v, OP_MustBeInt, regTemp, 0);
  
      /* If the parent table is the same as the child table, and we are about
      ** to increment the constraint-counter (i.e. this is an INSERT operation),
      ** then check if the row being inserted matches itself. If so, do not
      ** increment the constraint-counter.  */
      if( pTab==pFKey->pFrom && nIncr==1 ){
        sqlite3VdbeAddOp3(v, OP_Eq, regData, iOk, regTemp);
      }
  
      sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenRead);
      sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, regTemp);
      sqlite3VdbeAddOp2(v, OP_Goto, 0, iOk);
      sqlite3VdbeJumpHere(v, sqlite3VdbeCurrentAddr(v)-2);
      sqlite3VdbeJumpHere(v, iMustBeInt);
      sqlite3ReleaseTempReg(pParse, regTemp);
    }else{
      int nCol = pFKey->nCol;
      int regTemp = sqlite3GetTempRange(pParse, nCol);
      int regRec = sqlite3GetTempReg(pParse);
      KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
  
      sqlite3VdbeAddOp3(v, OP_OpenRead, iCur, pIdx->tnum, iDb);
      sqlite3VdbeChangeP4(v, -1, (char*)pKey, P4_KEYINFO_HANDOFF);
      for(i=0; i<nCol; i++){
        sqlite3VdbeAddOp2(v, OP_Copy, aiCol[i]+1+regData, regTemp+i);
      }
  
      /* If the parent table is the same as the child table, and we are about
      ** to increment the constraint-counter (i.e. this is an INSERT operation),
      ** then check if the row being inserted matches itself. If so, do not
      ** increment the constraint-counter. 
      **
      ** If any of the parent-key values are NULL, then the row cannot match 
      ** itself. So set JUMPIFNULL to make sure we do the OP_Found if any
      ** of the parent-key values are NULL (at this point it is known that
      ** none of the child key values are).
      */
      if( pTab==pFKey->pFrom && nIncr==1 ){
        int iJump = sqlite3VdbeCurrentAddr(v) + nCol + 1;
        for(i=0; i<nCol; i++){
          int iChild = aiCol[i]+1+regData;
          int iParent = pIdx->aiColumn[i]+1+regData;
          assert( aiCol[i]!=pTab->iPKey );
          if( pIdx->aiColumn[i]==pTab->iPKey ){
            /* The parent key is a composite key that includes the IPK column */
            iParent = regData;
          }
          sqlite3VdbeAddOp3(v, OP_Ne, iChild, iJump, iParent);
          sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL);
        }
        sqlite3VdbeAddOp2(v, OP_Goto, 0, iOk);
      }
  
      sqlite3VdbeAddOp3(v, OP_MakeRecord, regTemp, nCol, regRec);
      sqlite3VdbeChangeP4(v, -1, sqlite3IndexAffinityStr(v,pIdx), P4_TRANSIENT);
      sqlite3VdbeAddOp4Int(v, OP_Found, iCur, iOk, regRec, 0);
  
      sqlite3ReleaseTempReg(pParse, regRec);
      sqlite3ReleaseTempRange(pParse, regTemp, nCol);
    }
  }

  if( !pFKey->isDeferred && !pParse->pToplevel && !pParse->isMultiWrite ){
    /* Special case: If this is an INSERT statement that will insert exactly
    ** one row into the table, raise a constraint immediately instead of
    ** incrementing a counter. This is necessary as the VM code is being
    ** generated for will not open a statement transaction.  */
    assert( nIncr==1 );
    sqlite3HaltConstraint(
        pParse, OE_Abort, "foreign key constraint failed", P4_STATIC
    );
  }else{
    if( nIncr>0 && pFKey->isDeferred==0 ){
      sqlite3ParseToplevel(pParse)->mayAbort = 1;
    }
    sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, nIncr);
  }

  sqlite3VdbeResolveLabel(v, iOk);
  sqlite3VdbeAddOp1(v, OP_Close, iCur);
}
Ejemplo n.º 7
0
/*
** Generate code to do an analysis of all indices associated with
** a single table.
*/
static void analyzeOneTable(
  Parse *pParse,   /* Parser context */
  Table *pTab,     /* Table whose indices are to be analyzed */
  int iStatCur,    /* Cursor that writes to the sqlite_stat1 table */
  int iMem         /* Available memory locations begin here */
){
  Index *pIdx;     /* An index to being analyzed */
  int iIdxCur;     /* Cursor number for index being analyzed */
  int nCol;        /* Number of columns in the index */
  Vdbe *v;         /* The virtual machine being built up */
  int i;           /* Loop counter */
  int topOfLoop;   /* The top of the loop */
  int endOfLoop;   /* The end of the loop */
  int addr;        /* The address of an instruction */
  int iDb;         /* Index of database containing pTab */

  v = sqlite3GetVdbe(pParse);
  if( v==0 || pTab==0 || pTab->pIndex==0 ){
    /* Do no analysis for tables that have no indices */
    return;
  }
  assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
  assert( iDb>=0 );
#ifndef SQLITE_OMIT_AUTHORIZATION
  if( sqlite3AuthCheck(pParse, SQLITE_ANALYZE, pTab->zName, 0,
      pParse->db->aDb[iDb].zName ) ){
    return;
  }
#endif

  /* Establish a read-lock on the table at the shared-cache level. */
  sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);

  iIdxCur = pParse->nTab;
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);

    /* Open a cursor to the index to be analyzed
    */
    assert( iDb==sqlite3SchemaToIndex(pParse->db, pIdx->pSchema) );
    sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
    VdbeComment((v, "# %s", pIdx->zName));
    sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIdx->tnum,
        (char *)pKey, P3_KEYINFO_HANDOFF);
    nCol = pIdx->nColumn;
    if( iMem+nCol*2>=pParse->nMem ){
      pParse->nMem = iMem+nCol*2+1;
    }
    sqlite3VdbeAddOp(v, OP_SetNumColumns, iIdxCur, nCol+1);

    /* Memory cells are used as follows:
    **
    **    mem[iMem]:             The total number of rows in the table.
    **    mem[iMem+1]:           Number of distinct values in column 1
    **    ...
    **    mem[iMem+nCol]:        Number of distinct values in column N
    **    mem[iMem+nCol+1]       Last observed value of column 1
    **    ...
    **    mem[iMem+nCol+nCol]:   Last observed value of column N
    **
    ** Cells iMem through iMem+nCol are initialized to 0.  The others
    ** are initialized to NULL.
    */
    for(i=0; i<=nCol; i++){
      sqlite3VdbeAddOp(v, OP_MemInt, 0, iMem+i);
    }
    for(i=0; i<nCol; i++){
      sqlite3VdbeAddOp(v, OP_MemNull, iMem+nCol+i+1, 0);
    }

    /* Do the analysis.
    */
    endOfLoop = sqlite3VdbeMakeLabel(v);
    sqlite3VdbeAddOp(v, OP_Rewind, iIdxCur, endOfLoop);
    topOfLoop = sqlite3VdbeCurrentAddr(v);
    sqlite3VdbeAddOp(v, OP_MemIncr, 1, iMem);
    for(i=0; i<nCol; i++){
      sqlite3VdbeAddOp(v, OP_Column, iIdxCur, i);
      sqlite3VdbeAddOp(v, OP_MemLoad, iMem+nCol+i+1, 0);
      sqlite3VdbeAddOp(v, OP_Ne, 0x100, 0);
    }
    sqlite3VdbeAddOp(v, OP_Goto, 0, endOfLoop);
    for(i=0; i<nCol; i++){
      addr = sqlite3VdbeAddOp(v, OP_MemIncr, 1, iMem+i+1);
      sqlite3VdbeChangeP2(v, topOfLoop + 3*i + 3, addr);
      sqlite3VdbeAddOp(v, OP_Column, iIdxCur, i);
      sqlite3VdbeAddOp(v, OP_MemStore, iMem+nCol+i+1, 1);
    }
    sqlite3VdbeResolveLabel(v, endOfLoop);
    sqlite3VdbeAddOp(v, OP_Next, iIdxCur, topOfLoop);
    sqlite3VdbeAddOp(v, OP_Close, iIdxCur, 0);

    /* Store the results.  
    **
    ** The result is a single row of the sqlite_stat1 table.  The first
    ** two columns are the names of the table and index.  The third column
    ** is a string composed of a list of integer statistics about the
    ** index.  The first integer in the list is the total number of entires
    ** in the index.  There is one additional integer in the list for each
    ** column of the table.  This additional integer is a guess of how many
    ** rows of the table the index will select.  If D is the count of distinct
    ** values and K is the total number of rows, then the integer is computed
    ** as:
    **
    **        I = (K+D-1)/D
    **
    ** If K==0 then no entry is made into the sqlite_stat1 table.  
    ** If K>0 then it is always the case the D>0 so division by zero
    ** is never possible.
    */
    sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
    addr = sqlite3VdbeAddOp(v, OP_IfNot, 0, 0);
    sqlite3VdbeAddOp(v, OP_NewRowid, iStatCur, 0);
    sqlite3VdbeOp3(v, OP_String8, 0, 0, pTab->zName, 0);
    sqlite3VdbeOp3(v, OP_String8, 0, 0, pIdx->zName, 0);
    sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
    sqlite3VdbeOp3(v, OP_String8, 0, 0, " ", 0);
    for(i=0; i<nCol; i++){
      sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
      sqlite3VdbeAddOp(v, OP_MemLoad, iMem+i+1, 0);
      sqlite3VdbeAddOp(v, OP_Add, 0, 0);
      sqlite3VdbeAddOp(v, OP_AddImm, -1, 0);
      sqlite3VdbeAddOp(v, OP_MemLoad, iMem+i+1, 0);
      sqlite3VdbeAddOp(v, OP_Divide, 0, 0);
      sqlite3VdbeAddOp(v, OP_ToInt, 0, 0);
      if( i==nCol-1 ){
        sqlite3VdbeAddOp(v, OP_Concat, nCol*2-1, 0);
      }else{
        sqlite3VdbeAddOp(v, OP_Dup, 1, 0);
      }
    }
    sqlite3VdbeOp3(v, OP_MakeRecord, 3, 0, "aaa", 0);
    sqlite3VdbeAddOp(v, OP_Insert, iStatCur, OPFLAG_APPEND);
    sqlite3VdbeJumpHere(v, addr);
  }
}
Ejemplo n.º 8
0
/*
** Generate code to do an analysis of all indices associated with
** a single table.
*/
static void analyzeOneTable(
  Parse *pParse,   /* Parser context */
  Table *pTab,     /* Table whose indices are to be analyzed */
  Index *pOnlyIdx, /* If not NULL, only analyze this one index */
  int iStatCur,    /* Index of VdbeCursor that writes the sqlite_stat1 table */
  int iMem         /* Available memory locations begin here */
){
  sqlite3 *db = pParse->db;    /* Database handle */
  Index *pIdx;                 /* An index to being analyzed */
  int iIdxCur;                 /* Cursor open on index being analyzed */
  Vdbe *v;                     /* The virtual machine being built up */
  int i;                       /* Loop counter */
  int topOfLoop;               /* The top of the loop */
  int endOfLoop;               /* The end of the loop */
  int jZeroRows = -1;          /* Jump from here if number of rows is zero */
  int iDb;                     /* Index of database containing pTab */
  int regTabname = iMem++;     /* Register containing table name */
  int regIdxname = iMem++;     /* Register containing index name */
  int regSampleno = iMem++;    /* Register containing next sample number */
  int regCol = iMem++;         /* Content of a column analyzed table */
  int regRec = iMem++;         /* Register holding completed record */
  int regTemp = iMem++;        /* Temporary use register */
  int regRowid = iMem++;       /* Rowid for the inserted record */

#ifdef SQLITE_ENABLE_STAT2
  int addr = 0;                /* Instruction address */
  int regTemp2 = iMem++;       /* Temporary use register */
  int regSamplerecno = iMem++; /* Index of next sample to record */
  int regRecno = iMem++;       /* Current sample index */
  int regLast = iMem++;        /* Index of last sample to record */
  int regFirst = iMem++;       /* Index of first sample to record */
#endif

  v = sqlite3GetVdbe(pParse);
  if( v==0 || NEVER(pTab==0) ){
    return;
  }
  if( pTab->tnum==0 ){
    /* Do not gather statistics on views or virtual tables */
    return;
  }
  if( memcmp(pTab->zName, "sqlite_", 7)==0 ){
    /* Do not gather statistics on system tables */
    return;
  }
  assert( sqlite3BtreeHoldsAllMutexes(db) );
  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
  assert( iDb>=0 );
  assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
#ifndef SQLITE_OMIT_AUTHORIZATION
  if( sqlite3AuthCheck(pParse, SQLITE_ANALYZE, pTab->zName, 0,
      db->aDb[iDb].zName ) ){
    return;
  }
#endif

  /* Establish a read-lock on the table at the shared-cache level. */
  sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);

  iIdxCur = pParse->nTab++;
  sqlite3VdbeAddOp4(v, OP_String8, 0, regTabname, 0, pTab->zName, 0);
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    int nCol;
    KeyInfo *pKey;

    if( pOnlyIdx && pOnlyIdx!=pIdx ) continue;
    nCol = pIdx->nColumn;
    pKey = sqlite3IndexKeyinfo(pParse, pIdx);
    if( iMem+1+(nCol*2)>pParse->nMem ){
      pParse->nMem = iMem+1+(nCol*2);
    }

    /* Open a cursor to the index to be analyzed. */
    assert( iDb==sqlite3SchemaToIndex(db, pIdx->pSchema) );
    sqlite3VdbeAddOp4(v, OP_OpenRead, iIdxCur, pIdx->tnum, iDb,
        (char *)pKey, P4_KEYINFO_HANDOFF);
    VdbeComment((v, "%s", pIdx->zName));

    /* Populate the register containing the index name. */
    sqlite3VdbeAddOp4(v, OP_String8, 0, regIdxname, 0, pIdx->zName, 0);

#ifdef SQLITE_ENABLE_STAT2

    /* If this iteration of the loop is generating code to analyze the
    ** first index in the pTab->pIndex list, then register regLast has
    ** not been populated. In this case populate it now.  */
    if( pTab->pIndex==pIdx ){
      sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES, regSamplerecno);
      sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES*2-1, regTemp);
      sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES*2, regTemp2);

      sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regLast);
      sqlite3VdbeAddOp2(v, OP_Null, 0, regFirst);
      addr = sqlite3VdbeAddOp3(v, OP_Lt, regSamplerecno, 0, regLast);
      sqlite3VdbeAddOp3(v, OP_Divide, regTemp2, regLast, regFirst);
      sqlite3VdbeAddOp3(v, OP_Multiply, regLast, regTemp, regLast);
      sqlite3VdbeAddOp2(v, OP_AddImm, regLast, SQLITE_INDEX_SAMPLES*2-2);
      sqlite3VdbeAddOp3(v, OP_Divide,  regTemp2, regLast, regLast);
      sqlite3VdbeJumpHere(v, addr);
    }

    /* Zero the regSampleno and regRecno registers. */
    sqlite3VdbeAddOp2(v, OP_Integer, 0, regSampleno);
    sqlite3VdbeAddOp2(v, OP_Integer, 0, regRecno);
    sqlite3VdbeAddOp2(v, OP_Copy, regFirst, regSamplerecno);
#endif

    /* The block of memory cells initialized here is used as follows.
    **
    **    iMem:                
    **        The total number of rows in the table.
    **
    **    iMem+1 .. iMem+nCol: 
    **        Number of distinct entries in index considering the 
    **        left-most N columns only, where N is between 1 and nCol, 
    **        inclusive.
    **
    **    iMem+nCol+1 .. Mem+2*nCol:  
    **        Previous value of indexed columns, from left to right.
    **
    ** Cells iMem through iMem+nCol are initialized to 0. The others are 
    ** initialized to contain an SQL NULL.
    */
    for(i=0; i<=nCol; i++){
      sqlite3VdbeAddOp2(v, OP_Integer, 0, iMem+i);
    }
    for(i=0; i<nCol; i++){
      sqlite3VdbeAddOp2(v, OP_Null, 0, iMem+nCol+i+1);
    }

    /* Start the analysis loop. This loop runs through all the entries in
    ** the index b-tree.  */
    endOfLoop = sqlite3VdbeMakeLabel(v);
    sqlite3VdbeAddOp2(v, OP_Rewind, iIdxCur, endOfLoop);
    topOfLoop = sqlite3VdbeCurrentAddr(v);
    sqlite3VdbeAddOp2(v, OP_AddImm, iMem, 1);

    for(i=0; i<nCol; i++){
      CollSeq *pColl;
      sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regCol);
      if( i==0 ){
#ifdef SQLITE_ENABLE_STAT2
        /* Check if the record that cursor iIdxCur points to contains a
        ** value that should be stored in the sqlite_stat2 table. If so,
        ** store it.  */
        int ne = sqlite3VdbeAddOp3(v, OP_Ne, regRecno, 0, regSamplerecno);
        assert( regTabname+1==regIdxname 
             && regTabname+2==regSampleno
             && regTabname+3==regCol
        );
        sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL);
        sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 4, regRec, "aaab", 0);
        sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur+1, regRowid);
        sqlite3VdbeAddOp3(v, OP_Insert, iStatCur+1, regRec, regRowid);

        /* Calculate new values for regSamplerecno and regSampleno.
        **
        **   sampleno = sampleno + 1
        **   samplerecno = samplerecno+(remaining records)/(remaining samples)
        */
        sqlite3VdbeAddOp2(v, OP_AddImm, regSampleno, 1);
        sqlite3VdbeAddOp3(v, OP_Subtract, regRecno, regLast, regTemp);
        sqlite3VdbeAddOp2(v, OP_AddImm, regTemp, -1);
        sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES, regTemp2);
        sqlite3VdbeAddOp3(v, OP_Subtract, regSampleno, regTemp2, regTemp2);
        sqlite3VdbeAddOp3(v, OP_Divide, regTemp2, regTemp, regTemp);
        sqlite3VdbeAddOp3(v, OP_Add, regSamplerecno, regTemp, regSamplerecno);

        sqlite3VdbeJumpHere(v, ne);
        sqlite3VdbeAddOp2(v, OP_AddImm, regRecno, 1);
#endif

        /* Always record the very first row */
        sqlite3VdbeAddOp1(v, OP_IfNot, iMem+1);
      }
      assert( pIdx->azColl!=0 );
      assert( pIdx->azColl[i]!=0 );
      pColl = sqlite3LocateCollSeq(pParse, pIdx->azColl[i]);
      sqlite3VdbeAddOp4(v, OP_Ne, regCol, 0, iMem+nCol+i+1,
                       (char*)pColl, P4_COLLSEQ);
      sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
    }
    if( db->mallocFailed ){
      /* If a malloc failure has occurred, then the result of the expression 
      ** passed as the second argument to the call to sqlite3VdbeJumpHere() 
      ** below may be negative. Which causes an assert() to fail (or an
      ** out-of-bounds write if SQLITE_DEBUG is not defined).  */
      return;
    }
    sqlite3VdbeAddOp2(v, OP_Goto, 0, endOfLoop);
    for(i=0; i<nCol; i++){
      int addr2 = sqlite3VdbeCurrentAddr(v) - (nCol*2);
      if( i==0 ){
        sqlite3VdbeJumpHere(v, addr2-1);  /* Set jump dest for the OP_IfNot */
      }
      sqlite3VdbeJumpHere(v, addr2);      /* Set jump dest for the OP_Ne */
      sqlite3VdbeAddOp2(v, OP_AddImm, iMem+i+1, 1);
      sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, iMem+nCol+i+1);
    }

    /* End of the analysis loop. */
    sqlite3VdbeResolveLabel(v, endOfLoop);
    sqlite3VdbeAddOp2(v, OP_Next, iIdxCur, topOfLoop);
    sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);

    /* Store the results in sqlite_stat1.
    **
    ** The result is a single row of the sqlite_stat1 table.  The first
    ** two columns are the names of the table and index.  The third column
    ** is a string composed of a list of integer statistics about the
    ** index.  The first integer in the list is the total number of entries
    ** in the index.  There is one additional integer in the list for each
    ** column of the table.  This additional integer is a guess of how many
    ** rows of the table the index will select.  If D is the count of distinct
    ** values and K is the total number of rows, then the integer is computed
    ** as:
    **
    **        I = (K+D-1)/D
    **
    ** If K==0 then no entry is made into the sqlite_stat1 table.  
    ** If K>0 then it is always the case the D>0 so division by zero
    ** is never possible.
    */
    sqlite3VdbeAddOp2(v, OP_SCopy, iMem, regSampleno);
    if( jZeroRows<0 ){
      jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, iMem);
    }
    for(i=0; i<nCol; i++){
      sqlite3VdbeAddOp4(v, OP_String8, 0, regTemp, 0, " ", 0);
      sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regSampleno, regSampleno);
      sqlite3VdbeAddOp3(v, OP_Add, iMem, iMem+i+1, regTemp);
      sqlite3VdbeAddOp2(v, OP_AddImm, regTemp, -1);
      sqlite3VdbeAddOp3(v, OP_Divide, iMem+i+1, regTemp, regTemp);
      sqlite3VdbeAddOp1(v, OP_ToInt, regTemp);
      sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regSampleno, regSampleno);
    }
    sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
    sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regRowid);
    sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regRowid);
    sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
  }

  /* If the table has no indices, create a single sqlite_stat1 entry
  ** containing NULL as the index name and the row count as the content.
  */
  if( pTab->pIndex==0 ){
    sqlite3VdbeAddOp3(v, OP_OpenRead, iIdxCur, pTab->tnum, iDb);
    VdbeComment((v, "%s", pTab->zName));
    sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regSampleno);
    sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);
    jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, regSampleno);
  }else{
    sqlite3VdbeJumpHere(v, jZeroRows);
    jZeroRows = sqlite3VdbeAddOp0(v, OP_Goto);
  }
  sqlite3VdbeAddOp2(v, OP_Null, 0, regIdxname);
  sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
  sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regRowid);
  sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regRowid);
  sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
  if( pParse->nMem<regRec ) pParse->nMem = regRec;
  sqlite3VdbeJumpHere(v, jZeroRows);
}
Ejemplo n.º 9
0
/*
** Process an UPDATE statement.
**
**   UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL;
**          \_______/ \________/     \______/       \________________/
*            onError   pTabList      pChanges             pWhere
*/
void sqlite3Update(
  Parse *pParse,         /* The parser context */
  SrcList *pTabList,     /* The table in which we should change things */
  ExprList *pChanges,    /* Things to be changed */
  Expr *pWhere,          /* The WHERE clause.  May be null */
  int onError            /* How to handle constraint errors */
){
  int i, j;              /* Loop counters */
  Table *pTab;           /* The table to be updated */
  int addr = 0;          /* VDBE instruction address of the start of the loop */
  WhereInfo *pWInfo;     /* Information about the WHERE clause */
  Vdbe *v;               /* The virtual database engine */
  Index *pIdx;           /* For looping over indices */
  int nIdx;              /* Number of indices that need updating */
  int nIdxTotal;         /* Total number of indices */
  int iCur;              /* VDBE Cursor number of pTab */
  sqlite3 *db;           /* The database structure */
  Index **apIdx = 0;     /* An array of indices that need updating too */
  char *aIdxUsed = 0;    /* aIdxUsed[i]==1 if the i-th index is used */
  int *aXRef = 0;        /* aXRef[i] is the index in pChanges->a[] of the
                         ** an expression for the i-th column of the table.
                         ** aXRef[i]==-1 if the i-th column is not changed. */
  int chngRowid;         /* True if the record number is being changed */
  Expr *pRowidExpr = 0;  /* Expression defining the new record number */
  int openAll = 0;       /* True if all indices need to be opened */
  AuthContext sContext;  /* The authorization context */
  NameContext sNC;       /* The name-context to resolve expressions in */
  int iDb;               /* Database containing the table being updated */

#ifndef SQLITE_OMIT_TRIGGER
  int isView;                  /* Trying to update a view */
  int triggers_exist = 0;      /* True if any row triggers exist */
#endif

  int newIdx      = -1;  /* index of trigger "new" temp table       */
  int oldIdx      = -1;  /* index of trigger "old" temp table       */

  sContext.pParse = 0;
  if( pParse->nErr || sqlite3MallocFailed() ){
    goto update_cleanup;
  }
  db = pParse->db;
  assert( pTabList->nSrc==1 );

  /* Locate the table which we want to update. 
  */
  pTab = sqlite3SrcListLookup(pParse, pTabList);
  if( pTab==0 ) goto update_cleanup;
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);

  /* Figure out if we have any triggers and if the table being
  ** updated is a view
  */
#ifndef SQLITE_OMIT_TRIGGER
  triggers_exist = sqlite3TriggersExist(pParse, pTab, TK_UPDATE, pChanges);
  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 update_cleanup;
  }
  if( isView ){
    if( sqlite3ViewGetColumnNames(pParse, pTab) ){
      goto update_cleanup;
    }
  }
  aXRef = sqliteMallocRaw( sizeof(int) * pTab->nCol );
  if( aXRef==0 ) goto update_cleanup;
  for(i=0; i<pTab->nCol; i++) aXRef[i] = -1;

  /* If there are FOR EACH ROW triggers, allocate cursors for the
  ** special OLD and NEW tables
  */
  if( triggers_exist ){
    newIdx = pParse->nTab++;
    oldIdx = pParse->nTab++;
  }

  /* Allocate a cursors for the main database table and for all indices.
  ** The index cursors might not be used, but if they are used they
  ** need to occur right after the database cursor.  So go ahead and
  ** allocate enough space, just in case.
  */
  pTabList->a[0].iCursor = iCur = pParse->nTab++;
  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
    pParse->nTab++;
  }

  /* Initialize the name-context */
  memset(&sNC, 0, sizeof(sNC));
  sNC.pParse = pParse;
  sNC.pSrcList = pTabList;

  /* Resolve the column names in all the expressions of the
  ** of the UPDATE statement.  Also find the column index
  ** for each column to be updated in the pChanges array.  For each
  ** column to be updated, make sure we have authorization to change
  ** that column.
  */
  chngRowid = 0;
  for(i=0; i<pChanges->nExpr; i++){
    if( sqlite3ExprResolveNames(&sNC, pChanges->a[i].pExpr) ){
      goto update_cleanup;
    }
    for(j=0; j<pTab->nCol; j++){
      if( sqlite3StrICmp(pTab->aCol[j].zName, pChanges->a[i].zName)==0 ){
        if( j==pTab->iPKey ){
          chngRowid = 1;
          pRowidExpr = pChanges->a[i].pExpr;
        }
        aXRef[j] = i;
        break;
      }
    }
    if( j>=pTab->nCol ){
      if( sqlite3IsRowid(pChanges->a[i].zName) ){
        chngRowid = 1;
        pRowidExpr = pChanges->a[i].pExpr;
      }else{
        sqlite3ErrorMsg(pParse, "no such column: %s", pChanges->a[i].zName);
        goto update_cleanup;
      }
    }
#ifndef SQLITE_OMIT_AUTHORIZATION
    {
      int rc;
      rc = sqlite3AuthCheck(pParse, SQLITE_UPDATE, pTab->zName,
                           pTab->aCol[j].zName, db->aDb[iDb].zName);
      if( rc==SQLITE_DENY ){
        goto update_cleanup;
      }else if( rc==SQLITE_IGNORE ){
        aXRef[j] = -1;
      }
    }
#endif
  }

  /* Allocate memory for the array apIdx[] and fill it with pointers to every
  ** index that needs to be updated.  Indices only need updating if their
  ** key includes one of the columns named in pChanges or if the record
  ** number of the original table entry is changing.
  */
  for(nIdx=nIdxTotal=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdxTotal++){
    if( chngRowid ){
      i = 0;
    }else {
      for(i=0; i<pIdx->nColumn; i++){
        if( aXRef[pIdx->aiColumn[i]]>=0 ) break;
      }
    }
    if( i<pIdx->nColumn ) nIdx++;
  }
  if( nIdxTotal>0 ){
    apIdx = sqliteMallocRaw( sizeof(Index*) * nIdx + nIdxTotal );
    if( apIdx==0 ) goto update_cleanup;
    aIdxUsed = (char*)&apIdx[nIdx];
  }
  for(nIdx=j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
    if( chngRowid ){
      i = 0;
    }else{
      for(i=0; i<pIdx->nColumn; i++){
        if( aXRef[pIdx->aiColumn[i]]>=0 ) break;
      }
    }
    if( i<pIdx->nColumn ){
      apIdx[nIdx++] = pIdx;
      aIdxUsed[j] = 1;
    }else{
      aIdxUsed[j] = 0;
    }
  }

  /* Resolve the column names in all the expressions in the
  ** WHERE clause.
  */
  if( sqlite3ExprResolveNames(&sNC, pWhere) ){
    goto update_cleanup;
  }

  /* Start the view context
  */
  if( isView ){
    sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
  }

  /* Begin generating code.
  */
  v = sqlite3GetVdbe(pParse);
  if( v==0 ) goto update_cleanup;
  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
  sqlite3BeginWriteOperation(pParse, 1, iDb);

  /* If we are trying to update a view, realize that view into
  ** a ephemeral table.
  */
  if( isView ){
    Select *pView;
    pView = sqlite3SelectDup(pTab->pSelect);
    sqlite3Select(pParse, pView, SRT_VirtualTab, iCur, 0, 0, 0, 0);
    sqlite3SelectDelete(pView);
  }

  /* Begin the database scan
  */
  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0);
  if( pWInfo==0 ) goto update_cleanup;

  /* Remember the index of every item to be updated.
  */
  sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
  sqlite3VdbeAddOp(v, OP_FifoWrite, 0, 0);

  /* End the database scan loop.
  */
  sqlite3WhereEnd(pWInfo);

  /* Initialize the count of updated rows
  */
  if( db->flags & SQLITE_CountRows && !pParse->trigStack ){
    sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
  }

  if( triggers_exist ){
    /* Create pseudo-tables for NEW and OLD
    */
    sqlite3VdbeAddOp(v, OP_OpenPseudo, oldIdx, 0);
    sqlite3VdbeAddOp(v, OP_SetNumColumns, oldIdx, pTab->nCol);
    sqlite3VdbeAddOp(v, OP_OpenPseudo, newIdx, 0);
    sqlite3VdbeAddOp(v, OP_SetNumColumns, newIdx, pTab->nCol);

    /* The top of the update loop for when there are triggers.
    */
    addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, 0);

    if( !isView ){
      sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
      sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
      /* Open a cursor and make it point to the record that is
      ** being updated.
      */
      sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenRead);
    }
    sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);

    /* Generate the OLD table
    */
    sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
    sqlite3VdbeAddOp(v, OP_RowData, iCur, 0);
    sqlite3VdbeAddOp(v, OP_Insert, oldIdx, 0);

    /* Generate the NEW table
    */
    if( chngRowid ){
      sqlite3ExprCodeAndCache(pParse, pRowidExpr);
    }else{
      sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0);
    }
    for(i=0; i<pTab->nCol; i++){
      if( i==pTab->iPKey ){
        sqlite3VdbeAddOp(v, OP_Null, 0, 0);
        continue;
      }
      j = aXRef[i];
      if( j<0 ){
        sqlite3VdbeAddOp(v, OP_Column, iCur, i);
        sqlite3ColumnDefault(v, pTab, i);
      }else{
        sqlite3ExprCodeAndCache(pParse, pChanges->a[j].pExpr);
      }
    }
    sqlite3VdbeAddOp(v, OP_MakeRecord, pTab->nCol, 0);
    if( !isView ){
      sqlite3TableAffinityStr(v, pTab);
    }
    if( pParse->nErr ) goto update_cleanup;
    sqlite3VdbeAddOp(v, OP_Insert, newIdx, 0);
    if( !isView ){
      sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
    }

    /* Fire the BEFORE and INSTEAD OF triggers
    */
    if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TRIGGER_BEFORE, pTab,
          newIdx, oldIdx, onError, addr) ){
      goto update_cleanup;
    }
  }

  if( !isView ){
    /* 
    ** Open every index that needs updating.  Note that if any
    ** index could potentially invoke a REPLACE conflict resolution 
    ** action, then we need to open all indices because we might need
    ** to be deleting some records.
    */
    sqlite3OpenTable(pParse, iCur, iDb, pTab, OP_OpenWrite); 
    if( onError==OE_Replace ){
      openAll = 1;
    }else{
      openAll = 0;
      for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
        if( pIdx->onError==OE_Replace ){
          openAll = 1;
          break;
        }
      }
    }
    for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
      if( openAll || aIdxUsed[i] ){
        KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);
        sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
        sqlite3VdbeOp3(v, OP_OpenWrite, iCur+i+1, pIdx->tnum,
                       (char*)pKey, P3_KEYINFO_HANDOFF);
        assert( pParse->nTab>iCur+i+1 );
      }
    }

    /* Loop over every record that needs updating.  We have to load
    ** the old data for each record to be updated because some columns
    ** might not change and we will need to copy the old value.
    ** Also, the old data is needed to delete the old index entires.
    ** So make the cursor point at the old record.
    */
    if( !triggers_exist ){
      addr = sqlite3VdbeAddOp(v, OP_FifoRead, 0, 0);
      sqlite3VdbeAddOp(v, OP_Dup, 0, 0);
    }
    sqlite3VdbeAddOp(v, OP_NotExists, iCur, addr);

    /* If the record number will change, push the record number as it
    ** will be after the update. (The old record number is currently
    ** on top of the stack.)
    */
    if( chngRowid ){
      sqlite3ExprCode(pParse, pRowidExpr);
      sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
    }

    /* Compute new data for this record.  
    */
    for(i=0; i<pTab->nCol; i++){
      if( i==pTab->iPKey ){
        sqlite3VdbeAddOp(v, OP_Null, 0, 0);
        continue;
      }
      j = aXRef[i];
      if( j<0 ){
        sqlite3VdbeAddOp(v, OP_Column, iCur, i);
        sqlite3ColumnDefault(v, pTab, i);
      }else{
        sqlite3ExprCode(pParse, pChanges->a[j].pExpr);
      }
    }

    /* Do constraint checks
    */
    sqlite3GenerateConstraintChecks(pParse, pTab, iCur, aIdxUsed, chngRowid, 1,
                                   onError, addr);

    /* Delete the old indices for the current record.
    */
    sqlite3GenerateRowIndexDelete(db, v, pTab, iCur, aIdxUsed);

    /* If changing the record number, delete the old record.
    */
    if( chngRowid ){
      sqlite3VdbeAddOp(v, OP_Delete, iCur, 0);
    }

    /* Create the new index entries and the new record.
    */
    sqlite3CompleteInsertion(pParse, pTab, iCur, aIdxUsed, chngRowid, 1, -1);
  }

  /* Increment the row counter 
  */
  if( db->flags & SQLITE_CountRows && !pParse->trigStack){
    sqlite3VdbeAddOp(v, OP_AddImm, 1, 0);
  }

  /* If there are triggers, close all the cursors after each iteration
  ** through the loop.  The fire the after triggers.
  */
  if( triggers_exist ){
    if( !isView ){
      for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
        if( openAll || aIdxUsed[i] )
          sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0);
      }
      sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
    }
    if( sqlite3CodeRowTrigger(pParse, TK_UPDATE, pChanges, TRIGGER_AFTER, pTab, 
          newIdx, oldIdx, onError, addr) ){
      goto update_cleanup;
    }
  }

  /* Repeat the above with the next record to be updated, until
  ** all record selected by the WHERE clause have been updated.
  */
  sqlite3VdbeAddOp(v, OP_Goto, 0, addr);
  sqlite3VdbeJumpHere(v, addr);

  /* Close all tables if there were no FOR EACH ROW triggers */
  if( !triggers_exist ){
    for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
      if( openAll || aIdxUsed[i] ){
        sqlite3VdbeAddOp(v, OP_Close, iCur+i+1, 0);
      }
    }
    sqlite3VdbeAddOp(v, OP_Close, iCur, 0);
  }else{
    sqlite3VdbeAddOp(v, OP_Close, newIdx, 0);
    sqlite3VdbeAddOp(v, OP_Close, oldIdx, 0);
  }

  /*
  ** Return the number of rows that were changed. If this routine is 
  ** generating code because of a call to sqlite3NestedParse(), do not
  ** invoke the callback function.
  */
  if( db->flags & SQLITE_CountRows && !pParse->trigStack && pParse->nested==0 ){
    sqlite3VdbeAddOp(v, OP_Callback, 1, 0);
    sqlite3VdbeSetNumCols(v, 1);
    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows updated", P3_STATIC);
  }

update_cleanup:
  sqlite3AuthContextPop(&sContext);
  sqliteFree(apIdx);
  sqliteFree(aXRef);
  sqlite3SrcListDelete(pTabList);
  sqlite3ExprListDelete(pChanges);
  sqlite3ExprDelete(pWhere);
  return;
}