两种条件过滤合并到一个语句

[pengdeoo]

select a from tab where num = 0


select b from tab where num <> 0

合并到一个语句

[icelovey]

SELECT (CASE WHEN Num = 0 THEN A ELSE NULL END) AS A, 
   (CASE WHEN Num <> 0 THEN B ELSE NULL END) AS B
FROM Tab

??没太明白 , 这样?

[LongRui888]

引用 楼主 pengdeoo 的回复:

select a from tab where num = 0 select b from tab where num <> 0 合并到一个语句

你是想合并后，还是1列对吧,是这样吗:

--drop table tab

create table tab(a int,b int,num int)

insert into tab
select 1,2,100 union all
select 3,4,0


--注意字段a和字段b，是同一种数据类型
select case when num = 0
                 then a
            when num <> 0
                 then b
            else null
       end as xx
from tab
/*
xx
2
3
*/

[wyufen]

SELECT (CASE WHEN Num = 0 THEN A ELSE NULL END) AS A, (CASE WHEN Num <> 0 THEN B ELSE NULL END) AS B FROM Tab

[發糞塗牆]

SELECT *
FROM (select a from tab where num = 0
UNION ALL 
select b from tab where num <> 0)a

[Landa_Peter]

select case when num = 0
                 then a
            when num <> 0
                 then b
       end as C
from tab

[lis_mode]

select a, b from tab where ( num = 0 or num <> 0 )

[lis_mode]

搞错了。。。。。