CASE,GROUP BY用法

--create database dbTemp
use dbTemp
create table test
(
Pid int identity(1,1) not null primary key,
Years datetime,
IsFirstSixMonths int default(0), --0表示上半年1表示下半年--
TotalCome int
)
insert test
select '2007-1-1',0,50
union
select '2007-3-1',0,60
union
select '2007-12-1',1,80
union
select  '2008-1-1',0,100
union
select  '2008-12-1',1,100

select * from test

select convert(char(4),Years,120) as 'year',
IsFirstSixMonths=case when IsFirstSixMonths=0 then '上半年' when IsFirstSixMonths=1 then '下半年' END ,
sum(totalcome) as 'sum' from test
group by IsFirstSixMonths,convert(char(4),Years,120)


select convert(char(4),Years,120) as 'year',
IsFirstSixMonths=case when IsFirstSixMonths=0 then '上半年' ELSE '下半年' END ,
sum(totalcome) as 'sum' from test
group by IsFirstSixMonths,convert(char(4),Years,120)

--DROP DATABASE dbtemp
结果如下:
2007    上半年    110
2007    下半年    80
2008    上半年    100
2008    下半年    100