sql 删除重复数据

第一步查出重复数据

    select id from phone_blacklist where (userid,phone) in 
    (
        select userid,phone from phone_blacklist 
        group by userid,phone having count(*) > 1 
    )

第二步排除不想删除的第一条

    select id from phone_blacklist where (userid,phone) in 
    (
        select userid,phone from phone_blacklist 
        group by userid,phone having count(*) > 1 
    )
    and id not in
    (
        select min(id) from phone_blacklist 
        group by userid,phone having count(*) > 1 
    )

第三步开始删

delete from phone_blacklist where id in
(
    select id from
    (
        select id from phone_blacklist where (userid,phone) in 
        (
            select userid,phone from phone_blacklist 
            group by userid,phone having count(*) > 1 
        )
        and id not in
        (
            select min(id) from phone_blacklist 
            group by userid,phone having count(*) > 1 
        )
    ) as a
);