表a : code name price
------------------
001 书 12
002 电脑 4000
003 笔 10表b: code sl
-------------------
001 2
002 2表c : code sl
------------------
001 0
002 0
003 0小弟想得到的结果是: code name price sl
-------------------------
001 书 12 2
002 电脑 4000 2
003 笔 10 0急,在sql server 2000里面
------------------
001 书 12
002 电脑 4000
003 笔 10表b: code sl
-------------------
001 2
002 2表c : code sl
------------------
001 0
002 0
003 0小弟想得到的结果是: code name price sl
-------------------------
001 书 12 2
002 电脑 4000 2
003 笔 10 0急,在sql server 2000里面
select a.*, c.* from a
inner join c
on a.code = c.code
from tabA A join tabC C on A.code=C.code
left join tabB B on C.code=B.code
select A.*,isnull(B.sl,C.sl) as sl
from 表A A join 表C C on A.code=C.code
left join 表B B on C.code=B.code
case sl when null then sl else 0 end
select d.code ,name,price ,sum(d.s1) from a, (select code,sl from b UNION select code,s1 from c) d group by d.code ,name,price where a.code=d.code
select d.code ,name,price ,sum(d.s1) from a, (select code,sl from b UNION select code,s1 from c) d where a.code=d.code group by d.code ,name,price