T-SQL检查重复字段1值，但不同FIELD2值

Question

我的情况是这样的：

我有一个表，像这样的结构（简体） -

CREATE TABLE [dbo].[pe_mem](
    [pm_member] [int] NULL, 
    [pm_surname] [char](50) NULL, 
    [pm_forename] [char](50) NULL, 
    [pm_rsi_num] [char](11) NULL 

) ON [PRIMARY] 

我需要运行一个查询找到所有具有相同 pm_rsi_num但不同 pm_surname的行。

任何人都可以帮我解决这个问题吗？

谢谢！

Answer 1

已存在的变体：

select * 
from pe_mem t1 
where exists 
(select null 
from pe_mem t2 
where t1.pm_rsi_num = t2.pm_rsi_num 
     and t1.pm_surname <> t2.pm_surname) 

单表扫描版本：

select pm_rsi_num 
from pe_mem 
group by pm_rsi_num 
having count(distinct pm_surname) > 1 

Answer 2

您可以使用自联接为：

select * 
from pe_mem t1 
join pe_mem t2 
on  t1.pm_rsi_num = t2.pm_rsi_num 
     and t1.pm_surname <> t2.pm_surname 

Answer 3

刚刚加入表背本身和使用标准作为连接标准：

select * from pe_mem as p1 
inner join pe_mem as p2 
on p1.pm_rsi_num = p2.pm_rsi_num 
    and p1.pm_surname <> p2.pm_surname