删除记录

我有一个表[user_logs]具有以下字段[用户名]，[datetimelog]删除记录

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SQL删除查询删除所有用户登录EXCEPT他们最后的日志，以便上面的例子会产生一个DELETE查询

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

来源

2011-06-29 Lorence

我只知道DELETE FROM表WHERE ....但不知道如何通过这种情况下的条件。 – Lorence

什么后执行以下操作：

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.

可以工作吗？

来源

2011-06-29 08:27:53 cwallenpoole

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

这里删除一行，如果它不是在组的最大时间以相同USER_ID

来源

2011-06-29 08:31:54 Balanivash

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

试一下

来源

2011-06-29 08:32:50 gmhk

UL1.username = UL2.datetimelog应该是UL2.username – Friedrich

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