select max(dat) as dat from ( select * from a union all select * from b ) t
我按你的写的sql语句是: select max(dat1) as maxL,min(dat1) as minL,max(dat2) as maxR,min(dat2) as minR from (select * from datMN201004 union all select * from datMN) t where RtuID='00000115' and datTime like '2010-04-06%%'
from
(
select * from a union all select * from b
) t
select max(dat1) as maxL,min(dat1) as minL,max(dat2) as maxR,min(dat2) as minR from (select * from datMN201004 union all select * from datMN) t where RtuID='00000115' and datTime like '2010-04-06%%'