Mysql大数据表删除重复数据

对没有索引的字段进行查询重复时如果使用select name from table where name in(select name from table group by name having count(name)>1)这类查询，效率非常低，是不可取的，下面给出替代步骤：

1.根据重复记录创建临时表

create table   temptable as (

   select title from video

    GROUP BY title HAVING count(title) >1

);

2.查询重复数据

select a.* from temptable t,video a where a.title=t.title;

 

下面给出实际中我使用的删除重复数据的脚本，供参考：

create table   temptable as (   select MAX(id) as id  from video    GROUP BY title HAVING count(title) >1);delete  from video where id in (select id from temptable) order by id ;drop table temptable;