找到重复邮箱

编写一个 SQL 查询，查找 Person 表中所有重复的电子邮箱。

+----+---------+
| Id | Email |
+----+---------+
| 1 | a@b.com |
| 2 | c@d.com |
| 3 | a@b.com |
+----+---------+

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/duplicate-emails
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select email from Person group by email having count(email)>1

CREATE TABLE `Person` (
  `id` int(11) NOT NULL,
  `email` varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;

INSERT INTO `Person`(`id`, `email`) VALUES (1, 'a@b.com');
INSERT INTO `Person`(`id`, `email`) VALUES (2, 'c@d.com');
INSERT INTO `Person`(`id`, `email`) VALUES (3, 'a@b.com');