bug: derived table contains union all statement, return incorrect result set

[davidshiz]

Have you read the Contributing Guidelines on issues?

• I have read the Contributing Guidelines on issues.

Please confirm if bug report does NOT exists already ?

• I confirm there is no existing issue for this

Describe the problem

mysql> SELECT * FROM (SELECT a FROM t1 UNION ALL SELECT a FROM t2) tu ORDER BY a;
+-------+
| a     |
+-------+
| 65533 |
| 65533 |
|     0 |
|     0 |
|     1 |
|     1 |
+-------+
6 rows in set (0.00 sec)

Expected behavior

mysql> SELECT * FROM (SELECT a FROM t1 UNION ALL SELECT a FROM t2) tu ORDER BY a;
+-------+
| a     |
+-------+
|     0 |
|     0 |
|     1 |
|     1 |
|   253 |
| 65533 |
+-------+
6 rows in set (0.00 sec)

How To Reproduce

CREATE TABLE t1 (a TINYINT UNSIGNED);
INSERT INTO t1 VALUES (0),(1),(0xFF-2);
CREATE TABLE t2 (a SMALLINT UNSIGNED);
INSERT INTO t2 VALUES (0),(1),(0xFFFF-2);
SELECT * FROM (SELECT a FROM t1 UNION ALL SELECT a FROM t2) tu ORDER BY a;

Environment

[root@stonedb-test support-files]# /stonedb57/install/bin/mysqld --version
/stonedb57/install/bin/mysqld  Ver 5.7.36-StoneDB-v1.0.1 for Linux on x86_64 (build-)
build information as follow:
        Repository address: https://github.com/stoneatom/stonedb.git:stonedb-5.7-dev
        Branch name: stonedb-5.7-dev
        Last commit ID: 6b369e5
        Last commit time: Date:   Thu Jun 8 19:16:12 2023 +0800
        Build time: Date: Tue Jun 13 06:00:25 UTC 2023

Are you interested in submitting a PR to solve the problem?

• Yes, I will!