谢谢,有些疑问select * from tablename a where not exists(select 1 from tablename where type=a.type and id<a.id)select * from tablename a <-这个a是什么意思?exists(select 1 <-这个1是什么意思?
或者 SELECT * FROM TABLENAME A WHERE ID IN (SELECT TOP 1 ID FROM TABLENAME WHERE TYPE=A.TYPE ORDER BY 1 DESC)
SELECT * FROM TABLENAME A
WHERE ID IN
(SELECT TOP 1 ID FROM TABLENAME WHERE TYPE=A.TYPE ORDER BY 1 DESC)