Mysql 删除记录

我有一个表[user_logs]，其中包含以下字段[username]、[datetimelog]

样本数据

==============
user1   2011-06-28 08:49:01
user2   2011-06-28 08:59:38
user3   2011-06-28 09:04:31
user4   2011-06-28 10:00:15
user2   2011-06-28 10:28:54
user1   2011-06-29 08:31:22
user9   2011-06-29 08:32:32
user2   2011-06-29 10:13:53
user1   2011-06-29 13:11:15

我想知道如何创建一个SQLDELETE查询来删除除最后一个日志之外的所有用户日志，以便上面的示例在删除查询之后生成以下内容

user1   2011-06-29 13:11:15
user2   2011-06-29 10:13:53
user3   2011-06-28 09:04:31
user4   2011-06-28 10:00:15
user9   2011-06-29 08:32:32

那么：

DELETE FROM 
    MY_TABLE M -- delete from the table
LEFT JOIN
    MY_TABLE M2 ON M.user = M2.user -- table needs to be joined TO ITSELF
WHERE
    NOT M.LOG_DATE = MAX( M2.LOG_DATE ) -- Anything which isn't MAX goes.

那行吗

DELETE FROM table a WHERE time != (SELECT MAX(time) FROM table b WHERE b.user=a.user);

这里删除一行，如果它不是具有相同用户id的组中的最长时间

DELETE from user_logs UL1, user_logs UL2
where UL1.username =UL2.datetimelog
and UL1.datetimelog < UL2.datetimelog

---

试试看

我只知道从表中删除。。。。但是不知道如何为这种情况传递条件。UL1.username=UL2.datetimelog应该是UL2.username