刪除重復記錄的sql語句
我們提供了兩款刪除重復記錄的sql語句，一種是用id not in來實例，也算是聯合查詢的方法吧，第二種是臨時表來刪除重復記錄。
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
