-- 搜索出所有垃圾用户名:

select `hadoop_members`.`username` from `hadoop_members` left join `cdb_members` on `hadoop_members`.`username`=`cdb_members`.`username` where `cdb_members`.`username` is null;

select `hadoop_members`.`username` from `hadoop_members` where not exists (select `cdb_members`.`username` from `cdb_members` where `hadoop_members`.`username`=`cdb_members`.`username`);

 

-- 搜索出垃圾用户个数:

select count(`hadoop_members`.`username`) from `hadoop_members` left join `cdb_members` on `hadoop_members`.`username`=`cdb_members`.`username` where `cdb_members`.`username` is null;

select count(`hadoop_members`.`username`) from `hadoop_members` where not exists (select `cdb_members`.`username` from `cdb_members` where `hadoop_members`.`username`=`cdb_members`.`username`);

 

-- 删除垃圾用户

delete from `hadoop_members` where not exists (select 1 from `cdb_members` where `hadoop_members`.`username`=`cdb_members`.`username`);