SQLite

      */
      sqlite3VdbeAddOp0(v, OP_Goto);
      addrNextRow = sqlite3VdbeCurrentAddr(v);
      if( nColTest==1 && pIdx->nKeyCol==1 && IsUniqueIndex(pIdx) ){
        /* For a single-column UNIQUE index, once we have found a non-NULL
        ** row, we know that all the rest will be distinct, so skip 
        ** subsequent distinctness tests. */
        sqlite3VdbeAddOp2(v, OP_IfNotNull, regPrev, endDistinctTest);
        VdbeCoverage(v);
      }
      for(i=0; i<nColTest; i++){
        char *pColl = (char*)sqlite3LocateCollSeq(pParse, pIdx->azColl[i]);
        sqlite3VdbeAddOp2(v, OP_Integer, i, regChng);
        sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regTemp);
        aGotoChng[i] = 

      int addrIsNull;
      u8 seekOp = HasRowid(pTab) ? OP_NotExists : OP_NotFound;

      pParse->nMem = MAX(pParse->nMem, regCol+nCol);

      addrNext = sqlite3VdbeCurrentAddr(v);
      callStatGet(v, regStat4, STAT_GET_ROWID, regSampleRowid);
      addrIsNull = sqlite3VdbeAddOp1(v, OP_IfNull, regSampleRowid);
      VdbeCoverage(v);
      callStatGet(v, regStat4, STAT_GET_NEQ, regEq);
      callStatGet(v, regStat4, STAT_GET_NLT, regLt);
      callStatGet(v, regStat4, STAT_GET_NDLT, regDLt);
      sqlite3VdbeAddOp4Int(v, seekOp, iTabCur, addrNext, regSampleRowid, 0);
      /* We know that the regSampleRowid row exists because it was read by
      ** the previous loop.  Thus the not-found jump of seekOp will never

/*
** Return FALSE if there is no chance that the expression can be NULL.
**
** If the expression might be NULL or if the expression is too complex
** to tell return TRUE.  
**
** This routine is used as an optimization, to skip OP_IfNull opcodes
** when we know that a value cannot be NULL.  Hence, a false positive
** (returning TRUE when in fact the expression can never be NULL) might
** be a small performance hit but is otherwise harmless.  On the other
** hand, a false negative (returning FALSE when the result could be NULL)
** will likely result in an incorrect answer.  So when in doubt, return
** TRUE.
*/

  /* If the LHS is NULL, then the result is either false or NULL depending
  ** on whether the RHS is empty or not, respectively.
  */
  if( destIfNull==destIfFalse ){
    /* Shortcut for the common case where the false and NULL outcomes are
    ** the same. */
    sqlite3VdbeAddOp2(v, OP_IfNull, r1, destIfNull); VdbeCoverage(v);
  }else{
    int addr1 = sqlite3VdbeAddOp1(v, OP_IfNotNull, r1); VdbeCoverage(v);
    sqlite3VdbeAddOp2(v, OP_Rewind, pExpr->iTable, destIfFalse);
    VdbeCoverage(v);
    sqlite3VdbeAddOp2(v, OP_Goto, 0, destIfNull);
    sqlite3VdbeJumpHere(v, addr1);
  }

  if( eType==IN_INDEX_ROWID ){

      ** then the answer is TRUE the presence of NULLs in the RHS does
      ** not matter.  If the LHS is not contained in the RHS, then the
      ** answer is NULL if the RHS contains NULLs and the answer is
      ** FALSE if the RHS is NULL-free.
      */
      j1 = sqlite3VdbeAddOp4Int(v, OP_Found, pExpr->iTable, 0, r1, 1);
      VdbeCoverage(v);
      sqlite3VdbeAddOp2(v, OP_IfNull, rRhsHasNull, destIfNull);
      VdbeCoverage(v);
      sqlite3VdbeAddOp2(v, OP_Goto, 0, destIfFalse);
      sqlite3VdbeJumpHere(v, j1);
    }
  }
  sqlite3ReleaseTempReg(pParse, r1);
  sqlite3ExprCachePop(pParse);

      inReg = target;
      sqlite3VdbeAddOp2(v, op, r1, inReg);
      break;
    }
    case TK_ISNULL:
    case TK_NOTNULL: {
      int addr;
      assert( TK_ISNULL==OP_IfNull );   testcase( op==TK_ISNULL );
      assert( TK_NOTNULL==OP_IfNotNull ); testcase( op==TK_NOTNULL );
      sqlite3VdbeAddOp2(v, OP_Integer, 1, target);
      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
      testcase( regFree1==0 );
      addr = sqlite3VdbeAddOp1(v, op, r1);
      VdbeCoverageIf(v, op==TK_ISNULL);
      VdbeCoverageIf(v, op==TK_NOTNULL);
      sqlite3VdbeAddOp2(v, OP_AddImm, target, -1);

      ** arguments past the first non-NULL argument.
      */
      if( pDef->funcFlags & SQLITE_FUNC_COALESCE ){
        int endCoalesce = sqlite3VdbeMakeLabel(v);
        assert( nFarg>=2 );
        sqlite3ExprCode(pParse, pFarg->a[0].pExpr, target);
        for(i=1; i<nFarg; i++){
          sqlite3VdbeAddOp2(v, OP_IfNotNull, target, endCoalesce);
          VdbeCoverage(v);
          sqlite3ExprCacheRemove(pParse, target, 1);
          sqlite3ExprCachePush(pParse);
          sqlite3ExprCode(pParse, pFarg->a[i].pExpr, target);
          sqlite3ExprCachePop(pParse);
        }
        sqlite3VdbeResolveLabel(v, endCoalesce);

      VdbeCoverageIf(v, op==TK_NE);
      testcase( regFree1==0 );
      testcase( regFree2==0 );
      break;
    }
    case TK_ISNULL:
    case TK_NOTNULL: {
      assert( TK_ISNULL==OP_IfNull );   testcase( op==TK_ISNULL );
      assert( TK_NOTNULL==OP_IfNotNull ); testcase( op==TK_NOTNULL );
      r1 = sqlite3ExprCodeTemp(pParse, pExpr->pLeft, &regFree1);
      sqlite3VdbeAddOp2(v, op, r1, dest);
      VdbeCoverageIf(v, op==TK_ISNULL);
      VdbeCoverageIf(v, op==TK_NOTNULL);
      testcase( regFree1==0 );
      break;
    }

  if( NEVER(v==0) ) return; /* Existence of VDBE checked by caller */
  if( pExpr==0 )    return;

  /* The value of pExpr->op and op are related as follows:
  **
  **       pExpr->op            op
  **       ---------          ----------
  **       TK_ISNULL          OP_IfNotNull
  **       TK_NOTNULL         OP_IfNull
  **       TK_NE              OP_Eq
  **       TK_EQ              OP_Ne
  **       TK_GT              OP_Le
  **       TK_LE              OP_Gt
  **       TK_GE              OP_Lt
  **       TK_LT              OP_Ge
  **
  ** For other values of pExpr->op, op is undefined and unused.
  ** The value of TK_ and OP_ constants are arranged such that we
  ** can compute the mapping above using the following expression.
  ** Assert()s verify that the computation is correct.
  */
  op = ((pExpr->op+(TK_ISNULL&1))^1)-(TK_ISNULL&1);

  /* Verify correct alignment of TK_ and OP_ constants
  */
  assert( pExpr->op!=TK_ISNULL || op==OP_IfNotNull );
  assert( pExpr->op!=TK_NOTNULL || op==OP_IfNull );
  assert( pExpr->op!=TK_NE || op==OP_Eq );
  assert( pExpr->op!=TK_EQ || op==OP_Ne );
  assert( pExpr->op!=TK_LT || op==OP_Ge );
  assert( pExpr->op!=TK_LE || op==OP_Gt );
  assert( pExpr->op!=TK_GT || op==OP_Le );
  assert( pExpr->op!=TK_GE || op==OP_Lt );

  ** search for a matching row in the parent table.  */
  if( nIncr<0 ){
    sqlite3VdbeAddOp2(v, OP_FkIfZero, pFKey->isDeferred, iOk);
    VdbeCoverage(v);
  }
  for(i=0; i<pFKey->nCol; i++){
    int iReg = aiCol[i] + regData + 1;
    sqlite3VdbeAddOp2(v, OP_IfNull, iReg, iOk); VdbeCoverage(v);
  }

  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 */

        ** missing, behave as if it is empty. i.e. decrement the relevant
        ** FK counter for each row of the current table with non-NULL keys.
        */
        Vdbe *v = sqlite3GetVdbe(pParse);
        int iJump = sqlite3VdbeCurrentAddr(v) + pFKey->nCol + 1;
        for(i=0; i<pFKey->nCol; i++){
          int iReg = pFKey->aCol[i].iFrom + regOld + 1;
          sqlite3VdbeAddOp2(v, OP_IfNull, iReg, iJump); VdbeCoverage(v);
        }
        sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, -1);
      }
      continue;
    }
    assert( pFKey->nCol==1 || (aiFree && pIdx) );

    int j1;
    int iRec;
    int memId = p->regCtr;

    iRec = sqlite3GetTempReg(pParse);
    assert( sqlite3SchemaMutexHeld(db, 0, pDb->pSchema) );
    sqlite3OpenTable(pParse, 0, p->iDb, pDb->pSchema->pSeqTab, OP_OpenWrite);
    j1 = sqlite3VdbeAddOp1(v, OP_IfNotNull, memId+1); VdbeCoverage(v);
    sqlite3VdbeAddOp2(v, OP_NewRowid, 0, memId+1);
    sqlite3VdbeJumpHere(v, j1);
    sqlite3VdbeAddOp3(v, OP_MakeRecord, memId-1, 2, iRec);
    sqlite3VdbeAddOp3(v, OP_Insert, 0, iRec, memId+1);
    sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
    sqlite3VdbeAddOp0(v, OP_Close);
    sqlite3ReleaseTempReg(pParse, iRec);

      assert( !withoutRowid );
      if( useTempTable ){
        sqlite3VdbeAddOp3(v, OP_Column, srcTab, ipkColumn, regCols);
      }else{
        assert( pSelect==0 );  /* Otherwise useTempTable is true */
        sqlite3ExprCode(pParse, pList->a[ipkColumn].pExpr, regCols);
      }
      j1 = sqlite3VdbeAddOp1(v, OP_IfNotNull, regCols); VdbeCoverage(v);
      sqlite3VdbeAddOp2(v, OP_Integer, -1, regCols);
      sqlite3VdbeJumpHere(v, j1);
      sqlite3VdbeAddOp1(v, OP_MustBeInt, regCols); VdbeCoverage(v);
    }

    /* Cannot have triggers on a virtual table. If it were possible,
    ** this block would have to account for hidden column.

      }
      /* If the PRIMARY KEY expression is NULL, then use OP_NewRowid
      ** to generate a unique primary key value.
      */
      if( !appendFlag ){
        int j1;
        if( !IsVirtual(pTab) ){
          j1 = sqlite3VdbeAddOp1(v, OP_IfNotNull, regRowid); VdbeCoverage(v);
          sqlite3VdbeAddOp3(v, OP_NewRowid, iDataCur, regRowid, regAutoinc);
          sqlite3VdbeJumpHere(v, j1);
        }else{
          j1 = sqlite3VdbeCurrentAddr(v);
          sqlite3VdbeAddOp2(v, OP_IfNull, regRowid, j1+2); VdbeCoverage(v);
        }
        sqlite3VdbeAddOp1(v, OP_MustBeInt, regRowid); VdbeCoverage(v);
      }
    }else if( IsVirtual(pTab) || withoutRowid ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regRowid);
    }else{
      sqlite3VdbeAddOp3(v, OP_NewRowid, iDataCur, regRowid, regAutoinc);

        sqlite3VdbeAddOp4(v, OP_HaltIfNull, SQLITE_CONSTRAINT_NOTNULL, onError,
                          regNewData+1+i, zMsg, P4_DYNAMIC);
        sqlite3VdbeChangeP5(v, P5_ConstraintNotNull);
        VdbeCoverage(v);
        break;
      }
      case OE_Ignore: {
        sqlite3VdbeAddOp2(v, OP_IfNull, regNewData+1+i, ignoreDest);
        VdbeCoverage(v);
        break;
      }
      default: {
        assert( onError==OE_Replace );
        j1 = sqlite3VdbeAddOp1(v, OP_IfNotNull, regNewData+1+i); VdbeCoverage(v);
        sqlite3ExprCode(pParse, pTab->aCol[i].pDflt, regNewData+1+i);
        sqlite3VdbeJumpHere(v, j1);
        break;
      }
    }
  }

  v = sqlite3GetVdbe(pParse);
  assert( v!=0 );
  assert( pTab->pSelect==0 );  /* This table is not a VIEW */
  for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
    if( aRegIdx[i]==0 ) continue;
    bAffinityDone = 1;
    if( pIdx->pPartIdxWhere ){
      sqlite3VdbeAddOp2(v, OP_IfNull, aRegIdx[i], sqlite3VdbeCurrentAddr(v)+2);
      VdbeCoverage(v);
    }
    sqlite3VdbeAddOp2(v, OP_IdxInsert, iIdxCur+i, aRegIdx[i]);
    pik_flags = 0;
    if( useSeekResult ) pik_flags = OPFLAG_USESEEKRESULT;
    if( IsPrimaryKeyIndex(pIdx) && !HasRowid(pTab) ){
      assert( pParse->nested==0 );

        addrOk = sqlite3VdbeMakeLabel(v);
        if( pParent && pIdx==0 ){
          int iKey = pFK->aCol[0].iFrom;
          assert( iKey>=0 && iKey<pTab->nCol );
          if( iKey!=pTab->iPKey ){
            sqlite3VdbeAddOp3(v, OP_Column, 0, iKey, regRow);
            sqlite3ColumnDefault(v, pTab, iKey, regRow);
            sqlite3VdbeAddOp2(v, OP_IfNull, regRow, addrOk); VdbeCoverage(v);
            sqlite3VdbeAddOp2(v, OP_MustBeInt, regRow, 
               sqlite3VdbeCurrentAddr(v)+3); VdbeCoverage(v);
          }else{
            sqlite3VdbeAddOp2(v, OP_Rowid, 0, regRow);
          }
          sqlite3VdbeAddOp3(v, OP_NotExists, i, 0, regRow); VdbeCoverage(v);
          sqlite3VdbeAddOp2(v, OP_Goto, 0, addrOk);
          sqlite3VdbeJumpHere(v, sqlite3VdbeCurrentAddr(v)-2);
        }else{
          for(j=0; j<pFK->nCol; j++){
            sqlite3ExprCodeGetColumnOfTable(v, pTab, 0,
                            aiCols ? aiCols[j] : pFK->aCol[j].iFrom, regRow+j);
            sqlite3VdbeAddOp2(v, OP_IfNull, regRow+j, addrOk); VdbeCoverage(v);
          }
          if( pParent ){
            sqlite3VdbeAddOp4(v, OP_MakeRecord, regRow, pFK->nCol, regKey,
                              sqlite3IndexAffinityStr(v,pIdx), pFK->nCol);
            sqlite3VdbeAddOp4Int(v, OP_Found, i, addrOk, regKey, 0);
            VdbeCoverage(v);
          }

      /* Make sure sufficient number of registers have been allocated */
      pParse->nMem = MAX( pParse->nMem, cnt+8 );

      /* Do the b-tree integrity checks */
      sqlite3VdbeAddOp3(v, OP_IntegrityCk, 2, cnt, 1);
      sqlite3VdbeChangeP5(v, (u8)i);
      addr = sqlite3VdbeAddOp1(v, OP_IfNull, 2); VdbeCoverage(v);
      sqlite3VdbeAddOp4(v, OP_String8, 0, 3, 0,
         sqlite3MPrintf(db, "*** in database %s ***\n", db->aDb[i].zName),
         P4_DYNAMIC);
      sqlite3VdbeAddOp3(v, OP_Move, 2, 4, 1);
      sqlite3VdbeAddOp3(v, OP_Concat, 4, 3, 2);
      sqlite3VdbeAddOp2(v, OP_ResultRow, 2, 1);
      sqlite3VdbeJumpHere(v, addr);

        for(j=0; j<pTab->nCol; j++){
          char *zErr;
          int jmp2, jmp3;
          if( j==pTab->iPKey ) continue;
          if( pTab->aCol[j].notNull==0 ) continue;
          sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, j, 3);
          sqlite3VdbeChangeP5(v, OPFLAG_TYPEOFARG);
          jmp2 = sqlite3VdbeAddOp1(v, OP_IfNotNull, 3); VdbeCoverage(v);
          sqlite3VdbeAddOp2(v, OP_AddImm, 1, -1); /* Decrement error limit */
          zErr = sqlite3MPrintf(db, "NULL value in %s.%s", pTab->zName,
                              pTab->aCol[j].zName);
          sqlite3VdbeAddOp4(v, OP_String8, 0, 3, 0, zErr, P4_DYNAMIC);
          sqlite3VdbeAddOp2(v, OP_ResultRow, 3, 1);
          jmp3 = sqlite3VdbeAddOp1(v, OP_IfPos, 1); VdbeCoverage(v);
          sqlite3VdbeAddOp0(v, OP_Halt);

            int uniqOk = sqlite3VdbeMakeLabel(v);
            int jmp6;
            int kk;
            for(kk=0; kk<pIdx->nKeyCol; kk++){
              int iCol = pIdx->aiColumn[kk];
              assert( iCol>=0 && iCol<pTab->nCol );
              if( pTab->aCol[iCol].notNull ) continue;
              sqlite3VdbeAddOp2(v, OP_IfNull, r1+kk, uniqOk);
              VdbeCoverage(v);
            }
            jmp6 = sqlite3VdbeAddOp1(v, OP_Next, iIdxCur+j); VdbeCoverage(v);
            sqlite3VdbeAddOp2(v, OP_Goto, 0, uniqOk);
            sqlite3VdbeJumpHere(v, jmp6);
            sqlite3VdbeAddOp4Int(v, OP_IdxGT, iIdxCur+j, uniqOk, r1,
                                 pIdx->nKeyCol); VdbeCoverage(v);

  if( okOnePass ){
    if( aToOpen[iDataCur-iBaseCur] ){
      assert( pPk!=0 );
      sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, labelBreak, regKey, nKey);
      VdbeCoverageNeverTaken(v);
    }
    labelContinue = labelBreak;
    sqlite3VdbeAddOp2(v, OP_IfNull, pPk ? regKey : regOldRowid, labelBreak);
    VdbeCoverage(v);
  }else if( pPk ){
    labelContinue = sqlite3VdbeMakeLabel(v);
    sqlite3VdbeAddOp2(v, OP_Rewind, iEph, labelBreak); VdbeCoverage(v);
    addrTop = sqlite3VdbeAddOp2(v, OP_RowKey, iEph, regKey);
    sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, labelContinue, regKey, 0);
    VdbeCoverage(v);

  VdbeBranchTaken(c!=0, 2);
  if( c ){
    pc = pOp->p2-1;
  }
  break;
}

/* Opcode: IfNull P1 P2 * * *
** Synopsis:  if r[P1]==NULL goto P2
**
** Jump to P2 if the value in register P1 is NULL.
*/
case OP_IfNull: {            /* same as TK_ISNULL, jump, in1 */
  pIn1 = &aMem[pOp->p1];
  VdbeBranchTaken( (pIn1->flags & MEM_Null)!=0, 2);
  if( (pIn1->flags & MEM_Null)!=0 ){
    pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: IfNotNull P1 P2 * * *
** Synopsis: if r[P1]!=NULL goto P2
**
** Jump to P2 if the value in register P1 is not NULL.  
*/
case OP_IfNotNull: {            /* same as TK_NOTNULL, jump, in1 */
  pIn1 = &aMem[pOp->p1];
  VdbeBranchTaken( (pIn1->flags & MEM_Null)==0, 2);
  if( (pIn1->flags & MEM_Null)==0 ){
    pc = pOp->p2 - 1;
  }
  break;
}

      pIn->iCur = iTab;
      if( eType==IN_INDEX_ROWID ){
        pIn->addrInTop = sqlite3VdbeAddOp2(v, OP_Rowid, iTab, iReg);
      }else{
        pIn->addrInTop = sqlite3VdbeAddOp3(v, OP_Column, iTab, 0, iReg);
      }
      pIn->eEndLoopOp = bRev ? OP_PrevIfOpen : OP_NextIfOpen;
      sqlite3VdbeAddOp1(v, OP_IfNull, iReg); VdbeCoverage(v);
    }else{
      pLevel->u.in.nIn = 0;
    }
#endif
  }
  disableTerm(pLevel, pTerm);
  return iReg;

      }
    }
    testcase( pTerm->eOperator & WO_ISNULL );
    testcase( pTerm->eOperator & WO_IN );
    if( (pTerm->eOperator & (WO_ISNULL|WO_IN))==0 ){
      Expr *pRight = pTerm->pExpr->pRight;
      if( sqlite3ExprCanBeNull(pRight) ){
        sqlite3VdbeAddOp2(v, OP_IfNull, regBase+j, pLevel->addrBrk);
        VdbeCoverage(v);
      }
      if( zAff ){
        if( sqlite3CompareAffinity(pRight, zAff[j])==SQLITE_AFF_NONE ){
          zAff[j] = SQLITE_AFF_NONE;
        }
        if( sqlite3ExprNeedsNoAffinityChange(pRight, zAff[j]) ){

    nConstraint = nEq;
    if( pRangeStart ){
      Expr *pRight = pRangeStart->pExpr->pRight;
      sqlite3ExprCode(pParse, pRight, regBase+nEq);
      if( (pRangeStart->wtFlags & TERM_VNULL)==0
       && sqlite3ExprCanBeNull(pRight)
      ){
        sqlite3VdbeAddOp2(v, OP_IfNull, regBase+nEq, addrNxt);
        VdbeCoverage(v);
      }
      if( zStartAff ){
        if( sqlite3CompareAffinity(pRight, zStartAff[nEq])==SQLITE_AFF_NONE){
          /* Since the comparison is to be performed with no conversions
          ** applied to the operands, set the affinity to apply to pRight to 
          ** SQLITE_AFF_NONE.  */

    if( pRangeEnd ){
      Expr *pRight = pRangeEnd->pExpr->pRight;
      sqlite3ExprCacheRemove(pParse, regBase+nEq, 1);
      sqlite3ExprCode(pParse, pRight, regBase+nEq);
      if( (pRangeEnd->wtFlags & TERM_VNULL)==0
       && sqlite3ExprCanBeNull(pRight)
      ){
        sqlite3VdbeAddOp2(v, OP_IfNull, regBase+nEq, addrNxt);
        VdbeCoverage(v);
      }
      if( sqlite3CompareAffinity(pRight, cEndAff)!=SQLITE_AFF_NONE
       && !sqlite3ExprNeedsNoAffinityChange(pRight, cEndAff)
      ){
        codeApplyAffinity(pParse, regBase+nEq, 1, &cEndAff);
      }