mysql 查询重复与删除重复数据

一、根据身份证查询重复数据

方法、select count(*) as repeat_count,sfzhm from gaj_gx_hjxx_copy1 group by sfzhm having repeat_count > 1;

二、过滤重复数据

方法1、select distinct name,age from test_01;
方法2、select name,age,gender from test_01 group by name;

三、删除重复数据

方法1、create table test_temp select name,age,gender from test_01 group by name;
drop table test_01;
alter table test_temp rename to test_01;

方法2、DELETE FROM table_a 
WHERE id IN 
(SELECT id FROM (SELECT id FROM table_a GROUP BY c_1,c_2 HAVING count(*) > 1)e);

四、两个表合并

insert into test_01 (name,age,gender) select name,age,gender from test_02;