-- 笨重方法

　　delete from

　　tb_person

　　WHERE

　　id NOT IN ( select id from (SELECT min(id) id FROM tb_person GROUP BY email having count(1) > 1) tm)

　　and email in ( select email from ( SELECT email FROM tb_person GROUP BY email having count(1) > 1)tm)

　　-- 获取最小id，排除id信息进行删除

　　DELETE from Person Where Id not in ( Select MIN(Id) as Id From Person Group by Email )