sql 去除重复记录的语句
表a：
id，name
表b：
id,aid,value
select case when a.name='ccc' then null else a.name end name,b.value from 表a a，表b b where a.id=b.aid
select nullif(a.name,'ccc') name ,b.value from 表a a，表b b where a.id=b.aid
生成测试数据表: [tb]
if object_id('[tb]') is not null
    drop table [tb]
go
create table [tb] ([name] [nvarchar](10),[value] [int])
insert into [tb]
select 'aaa','1' union all
select 'bbb','2' union all
select 'ccc','3' union all
select 'ccc','4' union all
select 'ccc','5'
-->sql查询如下:
select name = case [value]
                   when (
                            select min([value])
                            from tb
                            where name = t.name
                        ) then name
                   else ''
              end, [value]
from [tb] t
/*
name       value
---------- -----------
aaa        1
bbb        2
ccc        3
           4
           5
(5 行受影响)