我有两个表,来自女巫想要选择用户,系统和软。
软记录应该是最新的记录“ tstamp2 ”
第一:表系统
USER SYSTEM ltstamp
======-----======----===================
User1 LA1 2013-05-06 11:27:26
User2 LA2 2013-06-07 11:27:26
第二:表软件
Soft SYSTEM tstamp2
=====----=====------===================
Av1 LA1 2013-04-06 10:27:26
Av2 LA1 2013-05-06 11:27:26
Av1 LA2 2013-04-06 10:27:26
Av2 LA2 2013-06-07 11:27:26
答案 0 :(得分:3)
SELECT s.user, s.system, sw.max_tstamp, sw2.soft
FROM
systems s INNER JOIN (SELECT system, MAX(tstamp2) AS max_tstamp
FROM software
GROUP BY system) sw
ON s.system = sw.system INNER JOIN software sw2
ON s.system = sw2.system AND sw.max_tstamp=sw2.tstamp2
请参阅小提琴here。
答案 1 :(得分:1)
您需要一个子请求才能执行此操作。例如:
select * from systems
where ltstamp = (select top 1 ltstamp from systems order by ltstamp desc)
答案 2 :(得分:1)
试试这个,
select user, system,soft , min(tstamp2) tstamp2 from systems s inner join software w on s.SYSTEM=w.SYSTEM group by user