谢谢楼上的,可是如果我要查询的语句:
select a.name,sum(case when a.date = '20070731' then a.ye end)
,sum(case when a.date = '20070631' then a.ye end)
,sum(case when a.date = '20060731' then a.ye end)
from people a where a.date in ('20070731' ,'20070631' ,'20060731' )
现实用的时候people表还关联了很多个相关的表.
这样如何优化?