如歌根据指定字段的值选取不同的字段值？？

[sunfly028]

表结构如下：
F1 F2 F3 F4 F5
1 2 3 4 1
5 6 7 8 2
...

当F5=1时选取F1、F3字段
当F5=2时选取F2、F4字段

请问如何实现？谢谢~

[dawugui]

select f5 , 
       f1 = case when f5 = 1 then f1 else f3 end , 
       f2 = case when f5 = 2 then f2 else f4 end 
from tb 

[dawugui]

create table tb (F1 int, F2 int, F3 int, F4 int, F5 int)
insert into tb values( 1, 2, 3, 4, 1 )
insert into tb values( 5, 6, 7, 8, 2 )
go

select f5 , 
       f1 = case when f5 = 1 then f1 else f3 end , 
       f2 = case when f5 = 2 then f2 else f4 end 
from tb 

drop table tb

/*
f5          f1          f2          
----------- ----------- ----------- 
1           1           4
2           7           6

（所影响的行数为 2 行）
*/

[kk19840210]

select case f5 when 1 then f1 else f2 end,case f5 when 1 then f3 else f4 end from tab

[dawugui]

--上面写错了.
create table tb (F1 int, F2 int, F3 int, F4 int, F5 int)
insert into tb values( 1, 2, 3, 4, 1 )
insert into tb values( 5, 6, 7, 8, 2 )
go

select f5 , 
       f1 = case when f5 = 1 then f1 else f2 end , 
       f2 = case when f5 = 2 then f4 else f3 end 
from tb 

drop table tb

/*
f5          f1          f2          
----------- ----------- ----------- 
1           1           3
2           6           8

（所影响的行数为 2 行
*/

[wzy_love_sly]

declare @tb table (f1 int,f2 int,f3 int,f4 int,f5 int)
insert into @tb select 1,2,3,4,1
insert into @tb select 5,6,7,8,2

select
case when f5=1 then f1 when f5=2 then f2 end as f1,
case when f5=1 then f3 when f5=2 then f4 end as f2
from @tb

[wzy_love_sly]

1 3
6 8

[sunfly028]

谢谢两位了

[surpasslight]

create table tb (F1 int, F2 int, F3 int, F4 int, F5 int)
insert into tb values( 1, 2, 3, 4, 1 )
insert into tb values( 5, 6, 7, 8, 2 )

select f5 ,
f1 = case when f5 = 1 then f1 else f2 end ,
f2 = case when f5 = 2 then f4 else f3 end
from tb

drop table tb