!3326 【bugfixed】解决orderby 列的别名在distinct中也报错的问题

Merge pull request !3326 from laishenghao/distinct-alias

src/common/backend/parser/parse_clause.cpp

@@ -2426,7 +2426,9 @@ static void CheckOrderbyColumns(ParseState* pstate, List* targetList, bool isAgg
                     break;
                 }
             }
-        } else {
+        }
+
+        if (!isFound) {
             Node* refExpr = transformExpr(pstate, (Node*)colRef, EXPR_KIND_ORDER_BY);
             ListCell* tcell = nullptr;
             foreach(tcell, targetList) {

src/test/regress/expected/distinct.out

@@ -1093,5 +1093,39 @@ LINE 1: ...elect a, min(b), group_concat(distinct c order by d) as orde...
                                                              ^
 CONTEXT:  referenced column: order_not_in_distinct
 reset group_concat_max_len;
+-- 12. test alias default
+create table dob_alias_only(
+	c1 int,
+	c2 int
+);
+insert into dob_alias_only values(1, 2);
+insert into dob_alias_only values(2, 1);
+insert into dob_alias_only values(2, 1);
+reset behavior_compat_options;
+select distinct c1 as a1 from dob_alias_only order by c1;
+ a1 
+----
+  1
+  2
+(2 rows)
+
+select distinct c1 as c2, c2 as c1 from dob_alias_only order by c1;
+ c2 | c1 
+----+----
+  2 |  1
+  1 |  2
+(2 rows)
+
+select distinct c1 as c2, c2 as c1 from dob_alias_only order by c2;
+ c2 | c1 
+----+----
+  1 |  2
+  2 |  1
+(2 rows)
+
+select distinct c1 + 1 as a1, c2 + 2 as a2 from dob_alias_only order by c1; -- should error
+ERROR:  for SELECT DISTINCT, ORDER BY expressions must appear in select list
+LINE 1: ... c1 + 1 as a1, c2 + 2 as a2 from dob_alias_only order by c1;
+                                                                    ^
 \c postgres
 drop database dob_bdb;

src/test/regress/sql/distinct.sql

@@ -303,5 +303,20 @@ reset behavior_compat_options;
 select a, min(b), group_concat(distinct c order by d) as order_not_in_distinct from dob_func_t group by a order by a;
 reset group_concat_max_len;
 
+-- 12. test alias default
+create table dob_alias_only(
+	c1 int,
+	c2 int
+);
+insert into dob_alias_only values(1, 2);
+insert into dob_alias_only values(2, 1);
+insert into dob_alias_only values(2, 1);
+
+reset behavior_compat_options;
+select distinct c1 as a1 from dob_alias_only order by c1;
+select distinct c1 as c2, c2 as c1 from dob_alias_only order by c1;
+select distinct c1 as c2, c2 as c1 from dob_alias_only order by c2;
+select distinct c1 + 1 as a1, c2 + 2 as a2 from dob_alias_only order by c1; -- should error
+
 \c postgres
 drop database dob_bdb;