mysql中去除重复4步骤

库表中因为日期up_date没设置unique所以相同日期重复插入

删除重复记录（up_date本应该设unique的，导至up_date有重复）

共4步：

create table table_name1 select min(id) as id from table_name group by up_date;

create table table_name2 select table_name.* from table_name, table_name1 where table_name.id = table_name1.id;

drop table table_name;

rename table table_name2 to table_name;