假设我有以下内容的表:MySQL的GROUP BY子句验证
mysql> select * from test;
+----+------+
| id | val |
+----+------+
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 2 |
| 7 | 2 |
| 8 | 2 |
+----+------+
8 rows in set (0.00 sec)
mysql>
现在我运行错误的SQL查询与group by
条款并没有对id
列中的任意聚集和得到错误的结果:
mysql> select id, val from test group by val;
+----+------+
| id | val |
+----+------+
| 1 | 1 |
| 5 | 2 |
+----+------+
2 rows in set (0.00 sec)
mysql>
可以mysql客户端或可能一些其他工具验证此查询,并发出错误或警告使用group by
没有聚合?
+1关注此 – 2013-03-08 12:03:24