int dest,             /* Write results into this register */
  u8 op,                /* Comparison operator */
  u8 p5                 /* SQLITE_NULLEQ or zero */
){
  Vdbe *v = pParse->pVdbe;
  Expr *pLeft = pExpr->pLeft;
  Expr *pRight = pExpr->pRight;

  if( sqlite3ExprCheckComparison(pParse, pLeft, pRight)==0 ){
    int nLeft = sqlite3ExprVectorSize(pLeft);
    int i;
    int regLeft = 0;
    int regRight = 0;
    u8 opx = op;
    int addrDone = sqlite3VdbeMakeLabel(v);


    assert( pExpr->op==TK_EQ || pExpr->op==TK_NE 
         || pExpr->op==TK_IS || pExpr->op==TK_ISNOT 
         || pExpr->op==TK_LT || pExpr->op==TK_GT 
         || pExpr->op==TK_LE || pExpr->op==TK_GE 
    );
    assert( pExpr->op==op || (pExpr->op==TK_IS && op==TK_EQ)
              || (pExpr->op==TK_ISNOT && op==TK_NE) );
    assert( p5==0 || pExpr->op!=op );
    assert( p5==SQLITE_NULLEQ || pExpr->op==op );

    p5 |= SQLITE_STOREP2;
    if( opx==TK_LE ) opx = TK_LT;
    if( opx==TK_GE ) opx = TK_GT;

    regLeft = exprCodeSubselect(pParse, pLeft);
    regRight = exprCodeSubselect(pParse, pRight);

    for(i=0; 1 /*Loop exits by "break"*/; i++){
      int regFree1 = 0, regFree2 = 0;
      Expr *pL, *pR; 
      int r1, r2;
      assert( i>=0 && i<nLeft );
      if( i>0 ) sqlite3ExprCachePush(pParse);
      r1 = exprVectorRegister(pParse, pLeft, i, regLeft, &pL, &regFree1);
      r2 = exprVectorRegister(pParse, pRight, i, regRight, &pR, &regFree2);
      codeCompare(pParse, pL, pR, opx, r1, r2, dest, p5);
      testcase(op==OP_Lt); VdbeCoverageIf(v,op==OP_Lt);
      testcase(op==OP_Le); VdbeCoverageIf(v,op==OP_Le);
      testcase(op==OP_Gt); VdbeCoverageIf(v,op==OP_Gt);
      testcase(op==OP_Ge); VdbeCoverageIf(v,op==OP_Ge);
      testcase(op==OP_Eq); VdbeCoverageIf(v,op==OP_Eq);
      testcase(op==OP_Ne); VdbeCoverageIf(v,op==OP_Ne);
      sqlite3ReleaseTempReg(pParse, regFree1);
      sqlite3ReleaseTempReg(pParse, regFree2);
      if( i>0 ) sqlite3ExprCachePop(pParse);
      if( i==nLeft-1 ){
        break;
      }
      if( opx==TK_EQ ){
        sqlite3VdbeAddOp2(v, OP_IfNot, dest, addrDone); VdbeCoverage(v);
        p5 |= SQLITE_KEEPNULL;
      }else if( opx==TK_NE ){
        sqlite3VdbeAddOp2(v, OP_If, dest, addrDone); VdbeCoverage(v);
        p5 |= SQLITE_KEEPNULL;
      }else{
        assert( op==TK_LT || op==TK_GT || op==TK_LE || op==TK_GE );
        sqlite3VdbeAddOp2(v, OP_ElseNotEq, 0, addrDone);
        VdbeCoverageIf(v, op==TK_LT);
        VdbeCoverageIf(v, op==TK_GT);
        VdbeCoverageIf(v, op==TK_LE);
        VdbeCoverageIf(v, op==TK_GE);
        if( i==nLeft-2 ) opx = op;
      }
    }
    sqlite3VdbeResolveLabel(v, addrDone);
  }
}

#if SQLITE_MAX_EXPR_DEPTH>0
/*
** Check that argument nHeight is less than or equal to the maximum
** expression depth allowed. If it is not, leave an error message in
** pParse.
................................................................................
    }
    return 1;
  }
  return 0;
}
#endif

/*
** Expressions pLeft and pRight are the left and right sides of a comparison
** operator. If either pLeft or pRight is a vector and the other is not, or
** if they are both vectors but of a different size, leave an error message
** in the Parse object and return non-zero. Or, if there is no problem, 
** return 0.
*/
int sqlite3ExprCheckComparison(Parse *pParse, Expr *pLeft, Expr *pRight){
  int nLeft = sqlite3ExprVectorSize(pLeft);
  int nRight = sqlite3ExprVectorSize(pRight);
  if( nLeft!=nRight ){
    if( (pRight->flags & EP_xIsSelect) ){
      sqlite3SubselectError(pParse, nRight, nLeft);
    }else if( pLeft->flags & EP_xIsSelect ){
      sqlite3SubselectError(pParse, nLeft, nRight);
    }else{
      sqlite3ErrorMsg(pParse, "row value misused");
    }
    return 1;
  }
  return 0;
}

#ifndef SQLITE_OMIT_SUBQUERY
/*
** Generate code for an IN expression.
**
**      x IN (SELECT ...)
**      x IN (value, value, ...)
**

  int dest,             /* Write results into this register */
  u8 op,                /* Comparison operator */
  u8 p5                 /* SQLITE_NULLEQ or zero */
){
  Vdbe *v = pParse->pVdbe;
  Expr *pLeft = pExpr->pLeft;
  Expr *pRight = pExpr->pRight;


  int nLeft = sqlite3ExprVectorSize(pLeft);
  int i;
  int regLeft = 0;
  int regRight = 0;
  u8 opx = op;
  int addrDone = sqlite3VdbeMakeLabel(v);

  assert( nLeft==sqlite3ExprVectorSize(pRight) );
  assert( pExpr->op==TK_EQ || pExpr->op==TK_NE 
       || pExpr->op==TK_IS || pExpr->op==TK_ISNOT 
       || pExpr->op==TK_LT || pExpr->op==TK_GT 
       || pExpr->op==TK_LE || pExpr->op==TK_GE 
  );
  assert( pExpr->op==op || (pExpr->op==TK_IS && op==TK_EQ)
            || (pExpr->op==TK_ISNOT && op==TK_NE) );
  assert( p5==0 || pExpr->op!=op );
  assert( p5==SQLITE_NULLEQ || pExpr->op==op );

  p5 |= SQLITE_STOREP2;
  if( opx==TK_LE ) opx = TK_LT;
  if( opx==TK_GE ) opx = TK_GT;

  regLeft = exprCodeSubselect(pParse, pLeft);
  regRight = exprCodeSubselect(pParse, pRight);

  for(i=0; 1 /*Loop exits by "break"*/; i++){
    int regFree1 = 0, regFree2 = 0;
    Expr *pL, *pR; 
    int r1, r2;
    assert( i>=0 && i<nLeft );
    if( i>0 ) sqlite3ExprCachePush(pParse);
    r1 = exprVectorRegister(pParse, pLeft, i, regLeft, &pL, &regFree1);
    r2 = exprVectorRegister(pParse, pRight, i, regRight, &pR, &regFree2);
    codeCompare(pParse, pL, pR, opx, r1, r2, dest, p5);
    testcase(op==OP_Lt); VdbeCoverageIf(v,op==OP_Lt);
    testcase(op==OP_Le); VdbeCoverageIf(v,op==OP_Le);
    testcase(op==OP_Gt); VdbeCoverageIf(v,op==OP_Gt);
    testcase(op==OP_Ge); VdbeCoverageIf(v,op==OP_Ge);
    testcase(op==OP_Eq); VdbeCoverageIf(v,op==OP_Eq);
    testcase(op==OP_Ne); VdbeCoverageIf(v,op==OP_Ne);
    sqlite3ReleaseTempReg(pParse, regFree1);
    sqlite3ReleaseTempReg(pParse, regFree2);
    if( i>0 ) sqlite3ExprCachePop(pParse);
    if( i==nLeft-1 ){
      break;
    }
    if( opx==TK_EQ ){
      sqlite3VdbeAddOp2(v, OP_IfNot, dest, addrDone); VdbeCoverage(v);
      p5 |= SQLITE_KEEPNULL;
    }else if( opx==TK_NE ){
      sqlite3VdbeAddOp2(v, OP_If, dest, addrDone); VdbeCoverage(v);
      p5 |= SQLITE_KEEPNULL;
    }else{
      assert( op==TK_LT || op==TK_GT || op==TK_LE || op==TK_GE );
      sqlite3VdbeAddOp2(v, OP_ElseNotEq, 0, addrDone);
      VdbeCoverageIf(v, op==TK_LT);
      VdbeCoverageIf(v, op==TK_GT);
      VdbeCoverageIf(v, op==TK_LE);
      VdbeCoverageIf(v, op==TK_GE);
      if( i==nLeft-2 ) opx = op;
    }
  }
  sqlite3VdbeResolveLabel(v, addrDone);

}

#if SQLITE_MAX_EXPR_DEPTH>0
/*
** Check that argument nHeight is less than or equal to the maximum
** expression depth allowed. If it is not, leave an error message in
** pParse.
................................................................................
    }
    return 1;
  }
  return 0;
}
#endif
























#ifndef SQLITE_OMIT_SUBQUERY
/*
** Generate code for an IN expression.
**
**      x IN (SELECT ...)
**      x IN (value, value, ...)
**

        }
      }
      break;
    }
    case TK_VARIABLE: {
      notValid(pParse, pNC, "parameters", NC_IsCheck|NC_PartIdx|NC_IdxExpr);
      break;



























    }
  }
  return (pParse->nErr || pParse->db->mallocFailed) ? WRC_Abort : WRC_Continue;
}

/*
** pEList is a list of expressions which are really the result set of the

        }
      }
      break;
    }
    case TK_VARIABLE: {
      notValid(pParse, pNC, "parameters", NC_IsCheck|NC_PartIdx|NC_IdxExpr);
      break;
    }
    case TK_EQ:
    case TK_NE:
    case TK_LT:
    case TK_LE:
    case TK_GT:
    case TK_GE:
    case TK_IS:
    case TK_ISNOT: {
      int nLeft, nRight;
      if( pParse->db->mallocFailed ) break;
      assert( pExpr->pRight!=0 );
      assert( pExpr->pLeft!=0 );
      nLeft = sqlite3ExprVectorSize(pExpr->pLeft);
      nRight = sqlite3ExprVectorSize(pExpr->pRight);
      if( nLeft!=nRight ){
        testcase( pExpr->op==TK_EQ );
        testcase( pExpr->op==TK_NE );
        testcase( pExpr->op==TK_LT );
        testcase( pExpr->op==TK_LE );
        testcase( pExpr->op==TK_GT );
        testcase( pExpr->op==TK_GE );
        testcase( pExpr->op==TK_IS );
        testcase( pExpr->op==TK_ISNOT );
        sqlite3ErrorMsg(pParse, "row value misused");
      }
      break; 
    }
  }
  return (pParse->nErr || pParse->db->mallocFailed) ? WRC_Abort : WRC_Continue;
}

/*
** pEList is a list of expressions which are really the result set of the

void sqlite3BackupUpdate(sqlite3_backup *, Pgno, const u8 *);

#ifndef SQLITE_OMIT_SUBQUERY
int sqlite3ExprCheckIN(Parse*, Expr*);
#else
# define sqlite3ExprCheckIN(x,y) SQLITE_OK
#endif
int sqlite3ExprCheckComparison(Parse*, Expr*, Expr*);

#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
void sqlite3AnalyzeFunctions(void);
int sqlite3Stat4ProbeSetValue(
    Parse*,Index*,UnpackedRecord**,Expr*,int,int,int*);
int sqlite3Stat4ValueFromExpr(Parse*, Expr*, u8, sqlite3_value**);
void sqlite3Stat4ProbeFree(UnpackedRecord*);

void sqlite3BackupUpdate(sqlite3_backup *, Pgno, const u8 *);

#ifndef SQLITE_OMIT_SUBQUERY
int sqlite3ExprCheckIN(Parse*, Expr*);
#else
# define sqlite3ExprCheckIN(x,y) SQLITE_OK
#endif


#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
void sqlite3AnalyzeFunctions(void);
int sqlite3Stat4ProbeSetValue(
    Parse*,Index*,UnpackedRecord**,Expr*,int,int,int*);
int sqlite3Stat4ValueFromExpr(Parse*, Expr*, u8, sqlite3_value**);
void sqlite3Stat4ProbeFree(UnpackedRecord*);

  pTerm->eOperator = 0;
  if( allowedOp(op) ){
    int iCur, iColumn;
    Expr *pLeft = sqlite3ExprSkipCollate(pExpr->pLeft);
    Expr *pRight = sqlite3ExprSkipCollate(pExpr->pRight);
    u16 opMask = (pTerm->prereqRight & prereqLeft)==0 ? WO_ALL : WO_EQUIV;

    if( pRight && sqlite3ExprCheckComparison(pParse, pLeft, pRight) ){
      return;
    }

    if( pTerm->iField>0 ){
      assert( op==TK_IN );
      assert( pLeft->op==TK_VECTOR );
      pLeft = pLeft->x.pList->a[pTerm->iField-1].pExpr;
    }

    if( exprMightBeIndexed(pSrc, op, prereqLeft, pLeft, &iCur, &iColumn) ){
................................................................................
  if( pWC->op==TK_AND 
  && (pExpr->op==TK_EQ || pExpr->op==TK_IS)
  && sqlite3ExprIsVector(pExpr->pLeft)
  && ( (pExpr->pLeft->flags & EP_xIsSelect)==0 
    || (pExpr->pRight->flags & EP_xIsSelect)==0
  )){
    int nLeft = sqlite3ExprVectorSize(pExpr->pLeft);
    if( nLeft==sqlite3ExprVectorSize(pExpr->pRight) ){
      int i;
      for(i=0; i<sqlite3ExprVectorSize(pExpr->pLeft); i++){

        int idxNew;
        Expr *pNew;
        Expr *pLeft = sqlite3ExprForVectorField(pParse, pExpr->pLeft, i);
        Expr *pRight = sqlite3ExprForVectorField(pParse, pExpr->pRight, i);

        pNew = sqlite3PExpr(pParse, pExpr->op, pLeft, pRight, 0);
        idxNew = whereClauseInsert(pWC, pNew, TERM_DYNAMIC);
        exprAnalyze(pSrc, pWC, idxNew);
      }
      pTerm = &pWC->a[idxTerm];
      pTerm->wtFlags = TERM_CODED|TERM_VIRTUAL;  /* Disable the original */
      pTerm->eOperator = 0;
    }
  }

  /* If there is a vector IN term - e.g. "(a, b) IN (SELECT ...)" - create
  ** a virtual term for each vector component. The expression object
  ** used by each such virtual term is pExpr (the full vector IN(...) 
  ** expression). The WhereTerm.iField variable identifies the index within
  ** the vector on the LHS that the virtual term represents.  */

  pTerm->eOperator = 0;
  if( allowedOp(op) ){
    int iCur, iColumn;
    Expr *pLeft = sqlite3ExprSkipCollate(pExpr->pLeft);
    Expr *pRight = sqlite3ExprSkipCollate(pExpr->pRight);
    u16 opMask = (pTerm->prereqRight & prereqLeft)==0 ? WO_ALL : WO_EQUIV;





    if( pTerm->iField>0 ){
      assert( op==TK_IN );
      assert( pLeft->op==TK_VECTOR );
      pLeft = pLeft->x.pList->a[pTerm->iField-1].pExpr;
    }

    if( exprMightBeIndexed(pSrc, op, prereqLeft, pLeft, &iCur, &iColumn) ){
................................................................................
  if( pWC->op==TK_AND 
  && (pExpr->op==TK_EQ || pExpr->op==TK_IS)
  && sqlite3ExprIsVector(pExpr->pLeft)
  && ( (pExpr->pLeft->flags & EP_xIsSelect)==0 
    || (pExpr->pRight->flags & EP_xIsSelect)==0
  )){
    int nLeft = sqlite3ExprVectorSize(pExpr->pLeft);

    int i;
    assert( nLeft==sqlite3ExprVectorSize(pExpr->pRight) );
    for(i=0; i<nLeft; i++){
      int idxNew;
      Expr *pNew;
      Expr *pLeft = sqlite3ExprForVectorField(pParse, pExpr->pLeft, i);
      Expr *pRight = sqlite3ExprForVectorField(pParse, pExpr->pRight, i);

      pNew = sqlite3PExpr(pParse, pExpr->op, pLeft, pRight, 0);
      idxNew = whereClauseInsert(pWC, pNew, TERM_DYNAMIC);
      exprAnalyze(pSrc, pWC, idxNew);
    }
    pTerm = &pWC->a[idxTerm];
    pTerm->wtFlags = TERM_CODED|TERM_VIRTUAL;  /* Disable the original */
    pTerm->eOperator = 0;

  }

  /* If there is a vector IN term - e.g. "(a, b) IN (SELECT ...)" - create
  ** a virtual term for each vector component. The expression object
  ** used by each such virtual term is pExpr (the full vector IN(...) 
  ** expression). The WhereTerm.iField variable identifies the index within
  ** the vector on the LHS that the virtual term represents.  */

  CREATE TABLE t3(a TEXT,b TEXT,c TEXT,d TEXT,e TEXT,f TEXT);
  CREATE INDEX t3x ON t3(b,c,d,e,f);

  SELECT a FROM t3
    WHERE (c,d) IN (SELECT 'c','d' FROM dual)
    AND (a,b,e) IN (SELECT 'a','b','d' FROM dual);
}




























finish_test

  CREATE TABLE t3(a TEXT,b TEXT,c TEXT,d TEXT,e TEXT,f TEXT);
  CREATE INDEX t3x ON t3(b,c,d,e,f);

  SELECT a FROM t3
    WHERE (c,d) IN (SELECT 'c','d' FROM dual)
    AND (a,b,e) IN (SELECT 'a','b','d' FROM dual);
}

do_catchsql_test 11.1 {
  CREATE TABLE t11(a);
  SELECT * FROM t11 WHERE (a,a)<=1;
} {1 {row value misused}}
do_catchsql_test 11.2 {
  SELECT * FROM t11 WHERE (a,a)<1;
} {1 {row value misused}}
do_catchsql_test 11.3 {
  SELECT * FROM t11 WHERE (a,a)>=1;
} {1 {row value misused}}
do_catchsql_test 11.4 {
  SELECT * FROM t11 WHERE (a,a)>1;
} {1 {row value misused}}
do_catchsql_test 11.5 {
  SELECT * FROM t11 WHERE (a,a)==1;
} {1 {row value misused}}
do_catchsql_test 11.6 {
  SELECT * FROM t11 WHERE (a,a)<>1;
} {1 {row value misused}}
do_catchsql_test 11.7 {
  SELECT * FROM t11 WHERE (a,a) IS 1;
} {1 {row value misused}}
do_catchsql_test 11.8 {
  SELECT * FROM t11 WHERE (a,a) IS NOT 1;
} {1 {row value misused}}


finish_test

  CREATE TABLE c3(d);
}
do_catchsql_test 8.2 {
  SELECT * FROM c2 CROSS JOIN c3 WHERE 
    ( (a, b) == (SELECT x, y FROM c1) AND c3.d = c ) OR
    ( c == (SELECT x, y FROM c1) AND c3.d = c )
} {1 {sub-select returns 2 columns - expected 1}}

finish_test

  CREATE TABLE c3(d);
}
do_catchsql_test 8.2 {
  SELECT * FROM c2 CROSS JOIN c3 WHERE 
    ( (a, b) == (SELECT x, y FROM c1) AND c3.d = c ) OR
    ( c == (SELECT x, y FROM c1) AND c3.d = c )
} {1 {row value misused}}

finish_test

} {3 4}

# Try a select with more than one result column.
#
do_test subselect-1.2 {
  set v [catch {execsql {SELECT * FROM t1 WHERE a = (SELECT * FROM t1)}} msg]
  lappend v $msg
} {1 {sub-select returns 2 columns - expected 1}}

# A subselect without an aggregate.
#
do_test subselect-1.3a {
  execsql {SELECT b from t1 where a = (SELECT a FROM t1 WHERE b=2)}
} {2}
do_test subselect-1.3b {

} {3 4}

# Try a select with more than one result column.
#
do_test subselect-1.2 {
  set v [catch {execsql {SELECT * FROM t1 WHERE a = (SELECT * FROM t1)}} msg]
  lappend v $msg
} {1 {row value misused}}

# A subselect without an aggregate.
#
do_test subselect-1.3a {
  execsql {SELECT b from t1 where a = (SELECT a FROM t1 WHERE b=2)}
} {2}
do_test subselect-1.3b {