Question

mysql查询两个字段下重复数据的删除方法

我有一个数库表，表名为credit,里面有这几名数值，person_id,project_id等，我想查询，project_id和person_id,重复的数据，并删除project_credit_id值大的记录（就是只删除后面两条）。谢谢。
这个数据库里有很多这样子的数据，谢谢。





Answer 1

select * from credit
where project_credit_id in (
select max(project_credit_id) as project_credit_id from credit group by person_id,project_id having count(*)>1
)
这个是查询语句前提是project_credit_id是主键，你核对一下没有问题的话，就把
select *改为delete就可以了

Answer 2

删除重复的
DELETE from credit where project_credit_id NOT IN (
select t.project_credit_id(
select max(project_credit_id) as project_credit_id from credit group by person_id,project_id having count(*)>1
)t)