182. 查找重复的电子邮箱

+----+---------+
| 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。

# 创建表
CREATE TABLE `Person` (
  `id` int(11) NOT NULL,
  `email` varchar(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

# 插入测试数据
insert into Person (id,email) value (1,"a@b.com");
insert into Person (id,email) value (2,"c@d.com");
insert into Person (id,email) value (3,"a@b.com");

# 查找重复数据
select email from Person group by Email having count(email) > 1