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(*)&
Oracle 数据库中查询重复数据：
select * from employee group by emp_name having count (*)>1;
Oracle 查询可以删除的重复数据
select t1.* from employee t1 where (t1.emp_name) in (SELECT t2.emp_name from employee t2 group by emp_name having count (*)>1) and t1.emp_id n
刚开始，根据我的想法，这个很简单嘛，上sql语句
delete from zqzrdp where tel in (select min(dpxx_id) from zqzrdp group by tel having count(tel)>1);
执行，报错！！~！~
异常意为：你不能指定目标表的更新在FROM子句。傻了，MySQL 这样写，不行，让人郁闷。
难倒只能分步操作，蛋疼
以下是网友写的，同样是坑爹的代码，我机器上运行不了。
1. 查询需要删除的记录，会保留一条记录。
方法一 declare max integer,id integer declare cur_rows cursor local for select 主字段,count(*) from 表名 group by 主字段 having count(*) > 1 open cur_rows fetch cur_rows into id,max while fetch_status=0 begin select max = max -1 set rowcount max delete from
