Mysql删除重复的数据 Mysql数据去重复

MySQL数据库中查询重复数据 select * from employee group by emp_name having count (*)1; Mysql 查询可以删除的重复数据 select t1.* from employee t1 where (t1.emp_name) in (select t4.emp_name from (select t2.emp_name from em

MySQL数据库中查询重复数据

select * from employee group by emp_name having count (*)>1;

Mysql  查询可以删除的重复数据

select t1.* from employee t1 where (t1.emp_name) in (select t4.emp_name from (select t2.emp_name from employee t2 group by t2.emp_name having count(*)>1) t4) and t1.emp_id not in (select t5.emp_id from (select min(t3.emp_id) as emp_id from employee t3 group by t3.emp_name having count(*)>1) t5);

Mysql  删除重复的数据

delete t1 from employee t1 where (t1.emp_name) in (select t4.emp_name from (select t2.emp_name from employee t2 group by t2.emp_name having count(*)>1) t4) and t1.emp_id not in (select t5.emp_id from (select min(t3.emp_id) as emp_id from employee t3 group by t3.emp_name having count(*)>1) t5);