SQLite

    *pp = sqlite3WindowDup(db, 0, pWin);
    if( *pp==0 ) break;
    pp = &((*pp)->pNextWin);
  }

  return pRet;
}

/*
** Return true if it can be determined at compile time that expression 
** pExpr evaluates to a value that, when cast to an integer, is greater 
** than zero. False otherwise.
**
** If an OOM error occurs, this function sets the Parse.db.mallocFailed 
** flag and returns zero.
*/
static int windowExprGtZero(Parse *pParse, Expr *pExpr){
  int ret = 0;
  sqlite3 *db = pParse->db;
  sqlite3_value *pVal = 0;
  sqlite3ValueFromExpr(db, pExpr, db->enc, SQLITE_AFF_NUMERIC, &pVal);
  if( pVal && sqlite3_value_int(pVal)>0 ){
    ret = 1;
  }
  sqlite3ValueFree(pVal);
  return ret;
}

/*
** sqlite3WhereBegin() has already been called for the SELECT statement 
** passed as the second argument when this function is invoked. It generates
** code to populate the Window.regResult register for each window function 
** and invoke the sub-routine at instruction addrGosub once for each row.
** sqlite3WhereEnd() is always called before returning. 

  /* Figure out when rows may be deleted from the ephemeral table. There
  ** are four options - they may never be deleted (eDelete==0), they may 
  ** be deleted as soon as they are no longer part of the window frame
  ** (eDelete==WINDOW_AGGINVERSE), they may be deleted as after the row 
  ** has been returned to the caller (WINDOW_RETURN_ROW), or they may
  ** be deleted after they enter the frame (WINDOW_AGGSTEP). */
  switch( pMWin->eStart ){
    case TK_FOLLOWING:
      if( pMWin->eType!=TK_RANGE && windowExprGtZero(pParse, pMWin->pStart) ){




        s.eDelete = WINDOW_RETURN_ROW;
      }


      break;

    case TK_UNBOUNDED:
      if( windowCacheFrame(pMWin)==0 ){
        if( pMWin->eEnd==TK_PRECEDING ){
          if( pMWin->eType!=TK_RANGE && windowExprGtZero(pParse, pMWin->pEnd) ){
            s.eDelete = WINDOW_AGGSTEP;
          }
        }else{
          s.eDelete = WINDOW_RETURN_ROW;
        }
      }
      break;
    default:
      s.eDelete = WINDOW_AGGINVERSE;

do_execsql_test 11.2 {
  SELECT a, (SELECT y FROM t3 WHERE x=a), sum(a) OVER (ORDER BY a)
    FROM t1 ORDER BY a;
} {
  10 ten 10   15 fifteen 25   20 {} 65        20 {} 65   
  25 {} 90    30 thirty 150   30 thirty 150   50 {} 200
}

do_execsql_test 11.3.1 {
  SELECT a, sum(a) OVER win FROM t1
  WINDOW win AS (ORDER BY a ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)
} {
  10 10 15 25 20 45 20 65 25 90 30 120 30 150 50 200
}
do_execsql_test 11.3.2 {
  SELECT a, sum(a) OVER win FROM t1
  WINDOW win AS (ORDER BY a ROWS BETWEEN UNBOUNDED PRECEDING AND 0 FOLLOWING)
} {
  10 10 15 25 20 45 20 65 25 90 30 120 30 150 50 200
}
do_execsql_test 11.3.3 {
  SELECT a, sum(a) OVER win FROM t1
  WINDOW win AS (ORDER BY a ROWS BETWEEN UNBOUNDED PRECEDING AND 0 PRECEDING)
} {
  10 10 15 25 20 45 20 65 25 90 30 120 30 150 50 200
}

do_execsql_test 11.4.1 {
  SELECT y, group_concat(y, '.') OVER win FROM t3
  WINDOW win AS (
    ORDER BY y RANGE BETWEEN UNBOUNDED PRECEDING AND 10 PRECEDING
  );
} {
  fifteen fifteen 
  ten     fifteen.ten 
  thirty  fifteen.ten.thirty
}

finish_test