mysql查出重复记录

以下是在MySQL中查出重复记录的方法：

1.使用GROUP BY和HAVING语句

SELECT mail_id, COUNT(*) FROM table_name GROUP BY mail_id HAVING COUNT(*) > 1;

2.使用子查询

SELECT * FROM table_name WHERE mail_id IN (SELECT mail_id FROM table_name GROUP BY mail_id HAVING COUNT(*) > 1);

3.使用窗口函数

SELECT * FROM (SELECT *, ROW_NUMBER() OVER (PARTITION BY mail_id ORDER BY rowid) AS rn FROM table_name) t WHERE t.rn > 1;