使用主键获取重复记录

Question

我使用sqso我有3个字段:

ID        CustomerNo        Date
1           0009                9/9/2011
2           0009                9/9/2011
3           0009                9/9/2011
4           0010                9/9/2011

我想确定具有相同customerno和date的记录,并获得每个唯一ID.

ID        CustomerNo        Date
1           0009                9/9/2011
2           0009                9/9/2011
3           0009                9/9/2011

我怎样才能做到这一点？我试过这段代码:

SELECT DISTINCT S1.ID,  S1.customerno, S1.DATE
FROM TABLE AS S1
INNER JOIN TABLE AS S2
ON  S1.DATE=S2.DATE AND S1.CUSTOMERNO=S2.CUSTOMERNO 
AND S2.id <= S1.id
GROUP BY S1.customerno, S1.id , S1.DATE

但它也获得了第4号记录,不同的客户没有,但具有相同的日期.

我想只获得customerno和date中重复的那些.

Answer 1

如果我理解正确,则此查询会给出重复的客户编号和日期.(我的表名为"t";我不能使用"table"作为表名.)

select customerno, date
from t
group by customerno, date
having count(*) >= 2

要获取这些"重复"客户的ID号,请将其加入原始表.

select t.id, t.customerno, t.date
from t
inner join
    (select customerno, date
     from t
     group by customerno, date
     having count(*) >= 2) dups 
  on dups.customerno = t.customerno and dups.date = t.date