SQLite

** Walk the expression tree pExpr and increase the aggregate function
** depth (the Expr.op2 field) by N on every TK_AGG_FUNCTION node.
** This needs to occur when copying a TK_AGG_FUNCTION node from an
** outer query into an inner subquery.
**
** incrAggFunctionDepth(pExpr,n) is the main routine.  incrAggDepth(..)
** is a helper function - a callback for the tree walker.
**
** See also the sqlite3WindowExtraAggFuncDepth() routine in window.c
*/
static int incrAggDepth(Walker *pWalker, Expr *pExpr){
  if( pExpr->op==TK_AGG_FUNCTION ) pExpr->op2 += pWalker->u.n;
  return WRC_Continue;
}
static void incrAggFunctionDepth(Expr *pExpr, int N){
  if( N>0 ){

      }
      pList = sqlite3ExprListAppend(pParse, pList, pDup);
      if( pList ) pList->a[nInit+i].sortFlags = pAppend->a[i].sortFlags;
    }
  }
  return pList;
}

/*
** When rewriting a query, if the new subquery in the FROM clause
** contains TK_AGG_FUNCTION nodes that refer to an outer query,
** then we have to increase the Expr->op2 values of those nodes
** due to the extra subquery layer that was added.
**
** See also the incrAggDepth() routine in resolve.c
*/
static int sqlite3WindowExtraAggFuncDepth(Walker *pWalker, Expr *pExpr){
  if( pExpr->op==TK_AGG_FUNCTION
   && pExpr->op2>=pWalker->walkerDepth
  ){
    pExpr->op2++;
  }
  return WRC_Continue;
}

/*
** If the SELECT statement passed as the second argument does not invoke
** any SQL window functions, this function is a no-op. Otherwise, it 
** rewrites the SELECT statement so that window function xStep functions
** are invoked in the correct order as described under "SELECT REWRITING"
** at the top of this file.

    pSub = sqlite3SelectNew(
        pParse, pSublist, pSrc, pWhere, pGroupBy, pHaving, pSort, 0, 0
    );
    p->pSrc = sqlite3SrcListAppend(pParse, 0, 0, 0);
    if( p->pSrc ){
      Table *pTab2;
      Walker w;
      p->pSrc->a[0].pSelect = pSub;
      sqlite3SrcListAssignCursors(pParse, p->pSrc);
      pSub->selFlags |= SF_Expanded;
      pTab2 = sqlite3ResultSetOfSelect(pParse, pSub, SQLITE_AFF_NONE);
      pSub->selFlags |= (selFlags & SF_Aggregate);
      if( pTab2==0 ){
        /* Might actually be some other kind of error, but in that case
        ** pParse->nErr will be set, so if SQLITE_NOMEM is set, we will get
        ** the correct error message regardless. */
        rc = SQLITE_NOMEM;
      }else{
        memcpy(pTab, pTab2, sizeof(Table));
        pTab->tabFlags |= TF_Ephemeral;
        p->pSrc->a[0].pTab = pTab;
        pTab = pTab2;
        memset(&w, 0, sizeof(w));
        w.xExprCallback = sqlite3WindowExtraAggFuncDepth;
        w.xSelectCallback = sqlite3WalkerDepthIncrease;
        w.xSelectCallback2 = sqlite3WalkerDepthDecrease;
        sqlite3WalkSelect(&w, pSub);
      }
    }else{
      sqlite3SelectDelete(db, pSub);
    }
    if( db->mallocFailed ) rc = SQLITE_NOMEM;
    sqlite3DbFree(db, pTab);
  }

             RANGE BETWEEN 5 PRECEDING AND 0 PRECEDING );
} {
  1 356 356 4 
  2 399 399 2 
  3 158 158 2 
  4 938 938 4
}

# 2020-05-23
# ticket 7a5279a25c57adf1
#
reset_db
do_execsql_test 53.0 {
  CREATE TABLE a(c UNIQUE);
  INSERT INTO a VALUES(4),(0),(9),(-9);
  SELECT a.c
    FROM a
    JOIN a AS b ON a.c=4
    JOIN a AS e ON a.c=e.c
   WHERE a.c=(SELECT (SELECT coalesce(lead(2) OVER(),0) + sum(d.c))
                FROM a AS d
               WHERE a.c);
} {4 4 4 4}


finish_test