删除重复记录的sql语句

　　我们提供了两款删除重复记录的sql语句，一种是用id not in来实例，也算是联合查询的方法吧，第二种是临时表来删除重复记录。

　　1),delete from tablename where id not in (select max(id) from tablename group by col1,col2,...)

　　2),select distinct * into temp from tablename

　　delete from tablename

　　insert into tablename select * from temp