mysql删除重复数据，并保留一条

因为系统bug在对所在店铺的会员进行屏蔽的时候没有进行查重操作，导致在屏蔽表中出现了重复的数据，所以需要删除此表中姓名重复的数据，并保留其中的一条。模拟数据如下图:

第一条sql :

delete from t_black_list where sellerId = 120055122 and names in (
  select names from t_black_list where sellerId = 120055122 and types = 4 group by names having count(names) > 1
)
and id not in (
  select id from t_black_list where sellerId = 120055122 and types = 4 group by names having count(names) > 1
)

遇到了问题:

遇到You can’t specify target table ‘表名’ for update in FROM clause这样的错误，它的意思是说，不能先select出同一表中的某些值，再update这个表(在同一语句中)，即不能依据某字段值做判断再来更新某字段的值。

解决:(中间表过度)

 select * from t_black_list where sellerId = 120055122  and names in (
  SELECT a.names from (select names from t_black_list where sellerId = 120055122  and types = 4 group by names having count(names) > 1) a
)
and id not in (
  SELECT b.id  from (select id from t_black_list where sellerId = 120055122  and types = 4 group by names having count(names) > 1) b
)

注:
mysql group by 会选择id最小的那个