---以name字段分组

 select Name,COUNT(Name) as [count] from Permission group by Name-- having COUNT(Name)>1

 ---以name字段分组，筛选出有重复出现的字段 having 用于条件筛选 作用相当于where 区别where用于group by 之前，having用于之后

 select Name,COUNT(Name) as [count] from Permission group by Name having COUNT(Name)>1

 ---获取重复记录中最小的一项的ID号

 select min(ID),Name,COUNT(Name) as [count] from Permission group by Name having COUNT(Name)>1

 ---删除重复数据

 delete from Permission

 ---找出拥有相同数据的记录

 where Name in (select Name from Permission group by Name having COUNT(Name)>1)

 ---除了最小ID号的数据保留，其他的删除 (也可以用max(id))

 and ID not in (select min(ID) from Permission group by Name having COUNT(Name)>1)