一个托朋友写的SQL题,感觉还不错，分享下。

select a.lat from (select top 1 * from dbo.tb_gps20111228) as a

select b.lat from (select top 1 * from dbo.tb_gps20111229) as b

select A.lata+B.latb as LAT from 
(
select a.lat AS lata, 'SID' as sid from (select top 1 * from dbo.tb_gps20111228) as a
) as A
left join
(
select b.lat AS latb, 'sid' AS SID from (select top 1 * from dbo.tb_gps20111229) as b
) as B on A.sid=B.SID