sql - SQL查询、计数和分组依据

Question

如果我有这样的数据：

钥匙	姓名
1	担
2	汤姆
3	乔恩
4	汤姆
5	山姆
6	担

什么是 SQL 查询来带回Name重复 2 次或更多次的记录？

所以我想要的结果是

汤姆
担

Answer 1

再简单不过了……

Select Name, Count(Name) As Count 
    From Table
    Group By Name
    Having Count(Name) > 1
    Order By Count(Name) Desc

这也可以扩展到删除重复项：

Delete From Table
Where Key In (
    Select Max(Key)
        From Table
        Group By Name
        Having Count(Name) > 1
    )

Answer 2

select name from table group by name having count(name) > 1

Answer 3

这也可以通过将表与自身连接来完成，

SELECT DISTINCT t1.name
FROM    tbl t1
        INNER JOIN tbl t2
        ON      t1.name = t2.name
WHERE   t1.key         != t2.key;