SQLite

        sqlite3VdbeAddOp2(v, OP_Integer, 0, dest.iSDParm);
        VdbeComment((v, "Init EXISTS result"));
      }
      sqlite3ExprDelete(pParse->db, pSel->pLimit);
      pSel->pLimit = sqlite3PExpr(pParse, TK_INTEGER, 0, 0,
                                  &sqlite3IntTokens[1]);
      pSel->iLimit = 0;
      pSel->selFlags &= ~SF_MultiValue;
      if( sqlite3Select(pParse, pSel, &dest) ){
        return 0;
      }
      rReg = dest.iSDParm;
      ExprSetVVAProperty(pExpr, EP_NoReduce);
      break;
    }

%type select {Select*}
%destructor select {sqlite3SelectDelete(pParse->db, $$);}
%type selectnowith {Select*}
%destructor selectnowith {sqlite3SelectDelete(pParse->db, $$);}
%type oneselect {Select*}
%destructor oneselect {sqlite3SelectDelete(pParse->db, $$);}



%include {
  /*
  ** For a compound SELECT statement, make sure p->pPrior->pNext==p for
  ** all elements in the list.  And make sure list length does not exceed
  ** SQLITE_LIMIT_COMPOUND_SELECT.
  */
  void parserDoubleLinkSelect(Parse *pParse, Select *p){

    if( p->pPrior ){

      Select *pNext = 0, *pLoop;
      int mxSelect, cnt = 0;
      for(pLoop=p; pLoop; pNext=pLoop, pLoop=pLoop->pPrior, cnt++){
        pLoop->pNext = pNext;
        pLoop->selFlags |= SF_Compound;

      }

      if( (p->selFlags & SF_MultiValue)==0 && 

        (mxSelect = pParse->db->aLimit[SQLITE_LIMIT_COMPOUND_SELECT])>0 &&
        cnt>mxSelect
      ){
        sqlite3ErrorMsg(pParse, "too many terms in compound SELECT");
      }
    }
  }
}

select(A) ::= with(W) selectnowith(X). {
  Select *p = X;
  if( p ){
    p->pWith = W;
    parserDoubleLinkSelect(pParse, p);
  }else{
    sqlite3WithDelete(pParse->db, W);
  }
  A = p;
}

selectnowith(A) ::= oneselect(X).                      {A = X;}
%ifndef SQLITE_OMIT_COMPOUND_SELECT
selectnowith(A) ::= selectnowith(X) multiselect_op(Y) oneselect(Z).  {
  Select *pRhs = Z;
  if( pRhs && pRhs->pPrior ){
    SrcList *pFrom;
    Token x;
    x.n = 0;
    parserDoubleLinkSelect(pParse, pRhs);
    pFrom = sqlite3SrcListAppendFromTerm(pParse,0,0,0,&x,pRhs,0,0);
    pRhs = sqlite3SelectNew(pParse,0,pFrom,0,0,0,0,0,0,0);
  }
  if( pRhs ){
    pRhs->op = (u8)Y;
    pRhs->pPrior = X;
    pRhs->selFlags &= ~SF_MultiValue;
    if( Y!=TK_ALL ) pParse->hasCompound = 1;
  }else{
    sqlite3SelectDelete(pParse->db, X);
  }
  A = pRhs;
}
%type multiselect_op {int}

%type values {Select*}
%destructor values {sqlite3SelectDelete(pParse->db, $$);}
values(A) ::= VALUES LP nexprlist(X) RP. {
  A = sqlite3SelectNew(pParse,X,0,0,0,0,0,SF_Values,0,0);
}
values(A) ::= values(X) COMMA LP exprlist(Y) RP. {
  Select *pRight, *pLeft = X;
  pRight = sqlite3SelectNew(pParse,Y,0,0,0,0,0,SF_Values|SF_MultiValue,0,0);
  if( pLeft ) pLeft->selFlags &= ~SF_MultiValue;
  if( pRight ){
    pRight->op = TK_ALL;
    pLeft = X;
    pRight->pPrior = pLeft;
    A = pRight;
  }else{
    A = pLeft;
  }
}

// The "distinct" nonterminal is true (1) if the DISTINCT keyword is
// present and false (0) if it is not.
//
%type distinct {u16}

  Select *p,            /* The right-most of SELECTs to be coded */
  SelectDest *pDest     /* What to do with query results */
){
  Select *pPrior;
  int nExpr = p->pEList->nExpr;
  int nRow = 1;
  int rc = 0;

  assert( p->selFlags & SF_MultiValue );
  do{
    assert( p->selFlags & SF_Values );
    assert( p->op==TK_ALL || (p->op==TK_SELECT && p->pPrior==0) );
    assert( p->pLimit==0 );
    assert( p->pOffset==0 );
    if( p->pEList->nExpr!=nExpr ){
      selectWrongNumTermsError(pParse, p);

    sqlite3VdbeAddOp2(v, OP_OpenEphemeral, dest.iSDParm, p->pEList->nExpr);
    sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
    dest.eDest = SRT_Table;
  }

  /* Special handling for a compound-select that originates as a VALUES clause.
  */
  if( p->selFlags & SF_MultiValue ){
    rc = multiSelectValues(pParse, p, &dest);
    goto multi_select_end;
  }

  /* Make sure all SELECTs in the statement have the same number of elements
  ** in their result sets.
  */

  w.xExprCallback = exprWalkNoop;
  w.pParse = pParse;
  if( pParse->hasCompound ){
    w.xSelectCallback = convertCompoundSelectToSubquery;
    sqlite3WalkSelect(&w, pSelect);
  }
  w.xSelectCallback = selectExpander;
  if( (pSelect->selFlags & SF_MultiValue)==0 ){
    w.xSelectCallback2 = selectPopWith;
  }
  sqlite3WalkSelect(&w, pSelect);
}


#ifndef SQLITE_OMIT_SUBQUERY

#define SF_Resolved        0x0002  /* Identifiers have been resolved */
#define SF_Aggregate       0x0004  /* Contains aggregate functions */
#define SF_UsesEphemeral   0x0008  /* Uses the OpenEphemeral opcode */
#define SF_Expanded        0x0010  /* sqlite3SelectExpand() called on this */
#define SF_HasTypeInfo     0x0020  /* FROM subqueries have Table metadata */
#define SF_Compound        0x0040  /* Part of a compound query */
#define SF_Values          0x0080  /* Synthesized from VALUES clause */
#define SF_MultiValue      0x0100  /* Single VALUES term with multiple rows */
#define SF_NestedFrom      0x0200  /* Part of a parenthesized FROM clause */
#define SF_MaybeConvert    0x0400  /* Need convertCompoundSelectToSubquery() */
#define SF_Recursive       0x0800  /* The recursive part of a recursive CTE */
#define SF_MinMaxAgg       0x1000  /* Aggregate containing min() or max() */
#define SF_Converted       0x2000  /* By convertCompoundSelectToSubquery() */

} {1 2 3 4 5 6 3 2 1 2 3 1 1 2 3 2 1 3}
do_execsql_test select4-14.10 {
  SELECT (VALUES(1),(2),(3),(4))
} {1}
do_execsql_test select4-14.11 {
  SELECT (SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4)
} {1}
do_execsql_test select4-14.12 {
  VALUES(1) UNION VALUES(2);
} {1 2}
do_execsql_test select4-14.13 {
  VALUES(1),(2),(3) EXCEPT VALUES(2);
} {1 3}
do_execsql_test select4-14.14 {
  VALUES(1),(2),(3) EXCEPT VALUES(1),(3);
} {2}

finish_test