如题,解决思路如下:
1、首先我们需要找出拥有重复数据的记录
---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
查找拥有重复记录的数据
执行结果:
2、然后我们需要知道要要保留的记录的ID号,或者其他唯一标识字段
---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
获取需要保留记录的ID编号
执行结果:
3、组合前面两个数据查询条件,进行删除操作
---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)
删除重复数据,保留其中一条