题目
编写一个 SQL 查询,查找 Person 表中所有重复的电子邮箱。
示例:
+----+---------+ | Id | Email | +----+---------+ | 1 | a@b.com | | 2 | c@d.com | | 3 | a@b.com | +----+---------+
根据以上输入,你的查询应返回以下结果:
+---------+ | Email | +---------+ | a@b.com | +---------+
说明:所有电子邮箱都是小写字母。
解题
select Email from Person group by Email having count(Email)>1;