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我有一个低于mysql的查询。它返回了错误的值。请帮我解决这个问题

SELECT
    T1.PARENT_ID,
    GROUP_CONCAT(
        IF(T2.PROPERTIES IS NULL, "NA", T2.PROPERTIES)
        ORDER BY T1.ORDER_INDEX ASC
    ) AS DATA
FROM TABLE_1 T1
JOIN TABLE_2 T2
    ON T1.ID=T2.ID
WHERE T1.AUTHOR="123"
GROUP BY T1.PARENT_ID
ORDER BY T1.PARENT_ID;

Mysql版本==>5.0.27-standard-log

上述查询返回：

+-----------+---------------+
| parent_id | data          |
+-----------+---------------+
| 12345     | te,test1,test |
| 23456     | NA            |
+-----------+---------------+
2 rows in set (0.00 sec)

_ 但是，它应该是：

+-----------+---------------+
| parent_id | data          |
+-----------+---------------+
| 12345     | NA,test1,test |
| 23456     | NA            |
+-----------+---------------+
2 rows in set (0.00 sec)    

- - 表数据

mysql> select * from Table_1;
+----+-----------+--------+-------------+
| id | parent_id | author | order_index |
+----+-----------+--------+-------------+
|  1 | 12345     | 123    |           3 |
|  2 | 12345     | 123    |           1 |
|  3 | 23456     | 123    |           1 |
|  4 | 12345     | 123    |           2 |
+----+-----------+--------+-------------+
4 rows in set (0.00 sec)

mysql> select * from Table_2;
+----+------------+
| id | properties |
+----+------------+
|  1 | test       |
|  2 | NULL       |
|  3 | NULL       |
|  4 | test1      |
+----+------------+
4 rows in set (0.00 sec)

- - 表格模型

mysql> desc Table_1;
+-------------+-----------+------+-----+---------+-------+
| Field       | Type      | Null | Key | Default | Extra |
+-------------+-----------+------+-----+---------+-------+
| id          | int(11)   | NO   | PRI |         |       |
| parent_id   | char(100) | YES  |     | NULL    |       |
| author      | char(100) | YES  |     | NULL    |       |
| order_index | int(11)   | YES  |     | 0       |       |
+-------------+-----------+------+-----+---------+-------+
4 rows in set (0.00 sec)

mysql> desc Table_2;
+------------+---------+------+-----+---------+-------+
| Field      | Type    | Null | Key | Default | Extra |
+------------+---------+------+-----+---------+-------+
| id         | int(11) | NO   | PRI |         |       |
| properties | text    | YES  |     | NULL    |       |
+------------+---------+------+-----+---------+-------+
2 rows in set (0.00 sec)

---

它给出正确的结果@MKhalidJunaid是的，它在给定的链接中给出正确的结果。但是，在Mysql版本-5.0.27中不起作用。谢谢