2022-11-29：查找重复的电子邮箱。以下数据中a@b.com是重复的，请写出sql语句。
DROP TABLE IF EXISTS person;
CREATE TABLE person (
id int(11) NOT NULL,
email varchar(255) NOT NULL,
PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
INSERT INTO person VALUES ('1', 'a@b.com');
INSERT INTO person VALUES ('2', 'c@d.com');
INSERT INTO person VALUES ('3', 'a@b.com');
答案2022-11-29：
sql语句如下：
select email
from person
group by email
having count(email) > 1;
执行结果如下：
