sqlserver查询两个结构相似的表，按两表中的添加时间倒序的问题

http://topic.csdn.net/u/20110407/15/cfc8e39f-8a7d-4fec-af34-f3fe872bee36.html

 

select * from (
select top 5 protId,sortId,userId,regdate,'新表' tbname from tb1 order by regdate desc
union  
select top 5 protId,sortId,userId,regdate,'旧表' tbname from tb2 order by regdate desc
)as a
order by a.regdate desc