id call_id to_call_id call_time
-----------------------------------------
1 001 005 2008-2-6
2 001 005 2008-2-7
3 001 005 2008-2-8
4 002 005 2008-2-8
5 003 004 2008-2-9
显示结果:id call_id to_call_id call_time
-----------------------------------------
3 001 005 2008-2-8
4 002 005 2008-2-8
5 003 004 2008-2-9查询不重复记录,保留最新的一条
-----------------------------------------
1 001 005 2008-2-6
2 001 005 2008-2-7
3 001 005 2008-2-8
4 002 005 2008-2-8
5 003 004 2008-2-9
显示结果:id call_id to_call_id call_time
-----------------------------------------
3 001 005 2008-2-8
4 002 005 2008-2-8
5 003 004 2008-2-9查询不重复记录,保留最新的一条
(select call_id,max(call_time) as ma from tt group by call_id) b
on a.call_time=b.ma and a.call_id=b.call_id
select * from 表 a
where id in (select id from 表 where call_id=a.call_id order by call_time desc limit 1);
如果是联表查询呢?
比如:
id username to_call_id call_time
-----------------------------------------
1 zhan 005 2008-2-6
2 zhan 005 2008-2-7
3 zhan 005 2008-2-8
4 li 005 2008-2-8
5 wang 004 2008-2-9
显示结果: id username to_call_id call_time
-----------------------------------------
3 zhan 005 2008-2-8
4 li 005 2008-2-8
5 wang 004 2008-2-9call_id为外键 另表主键为id
什么意思?
以下代码可以解决select a.* from tt a inner join
(select username,max(call_time) as ma from tt group by username) b
on a.call_time=b.ma and a.username=b.username
id int(10) (NULL) NO PRI
call_id int(11) (NULL) YES
to_call_id int(11) (NULL) YES
call_time int(11) (NULL) 表2:
id int(10) (NULL) NO PRI
username varchar(20) (NULL) yes表1 call_id 与表2 id关联
select * from b1 inner join b2 on a.call_id=b2.id
字段自行调整select a.* from tt a inner join
(select username,max(call_time) as ma from tt group by username) b
on a.call_time=b.ma and a.username=b.username
select * from b1 inner join b2 on a.call_id=b2.id
两个地方
(select username,max(call_time) as ma from tt group by username) b
on a.call_time=b.ma and a.username=b.username将TT更换为
select * from b1 inner join b2 on a.call_id=b2.id
两个地方自己试试吧
from wd_call as c,dede_member as m where m.id=c.call_id
group by c.call_id,c.to_call_id
我试了一下这个,貌似可以
标准的SQL格式是什么??
from wd_call as c,dede_member as m where m.id=c.call_id
group by c.call_id,c.to_call_id