mysql> select * from tab1;
+----+------+
| id | c2 |
+----+------+
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 2 |
+----+------+
6 rows in set (0.00 sec)
mysql> select c2,group_concat(id order by id separator ',') from tab1 group by c
2;
+------+--------------------------------------------+
| c2 | group_concat(id order by id separator ',') |
+------+--------------------------------------------+
| 1 | 1,2,3,4 |
| 2 | 5,6 |
+------+--------------------------------------------+
2 rows in set (0.00 sec)
ORACLE也有这样的一个函数 wmsys.wm_concat()