MySQL 刪除重複資料
Feb 1, 2021
有一重複會員資料表，要刪除相同 Email 及 生日 資料。
查詢：
Select * from users
order by email, birth;
確認重複內容：
select email, birth count(*) as cnt
from users
group by email, birth having cnt > 1;
刪除重複：
delete t1 from users as t1
inner join users as t2
where t1.id > t2.id
and t1.email = t2.email
and t1.birth = t2.birth;
