mysql 使用特殊 id 和日期字段从查询中删除

Question

我在 tblSpecialTable 中有两列specialid和date，我的表有重复的specialID，我想从表中删除其中date列是较旧的日期并且specialid重复的地方。

Answer 1

看我的例子:

mysql> SELECT * FROM test;
+------+---------------------+
| id   | d                   |
+------+---------------------+
|    1 | 2011-06-29 10:48:41 | 
|    2 | 2011-06-29 10:48:44 | 
|    3 | 2011-06-29 10:48:46 | 
|    1 | 2011-06-29 10:48:52 | 
|    2 | 2011-06-29 10:48:53 | 
|    3 | 2011-06-29 10:48:55 | 
+------+---------------------+
mysql> DELETE t1 FROM test t1 INNER JOIN test t2 ON t1.id = t2.id AND t1.d < t2.d;
Query OK, 3 rows affected (0.00 sec)
mysql> SELECT * FROM test;
+------+---------------------+
| id   | d                   |
+------+---------------------+
|    1 | 2011-06-29 10:48:52 | 
|    2 | 2011-06-29 10:48:53 | 
|    3 | 2011-06-29 10:48:55 | 
+------+---------------------+

另请参阅http://dev.mysql.com/doc/refman/5.0/en/delete.html