1.1 KiB
1.1 KiB
182.查找重复的电子邮箱
2022-08-10 22:24:58
SQL架构
Create table If Not Exists Person
(
id int,
email varchar(255)
);
Truncate table Person;
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');
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。
Related Topics
- 数据库
解
select Email
from (select Email, count(Email) as num
from Person
group by Email) as statistic
where num > 1;
select Email
from Person
group by Email
having count(Email) > 1;