标签:重复 cat pre delete let mys 编写 -- 记录
编写一个 SQL 查询,来删除?Person?表中所有重复的电子邮箱,重复的邮箱里只保留?Id?最小?的那个。
+----+------------------+
| Id | Email |
+----+------------------+
| 1 | john@example.com |
| 2 | bob@example.com |
| 3 | john@example.com |
+----+------------------+
Id 是这个表的主键。
例如,在运行你的查询语句之后,上面的 Person 表应返回以下几行:
+----+------------------+
| Id | Email |
+----+------------------+
| 1 | john@example.com |
| 2 | bob@example.com |
+----+------------------+
来源:力扣(LeetCode)
链接:https://leetcode-cn.com/problems/delete-duplicate-emails
著作权归领扣网络所有。商业转载请联系官方授权,非商业转载请注明出处。
DELETE t1
FROM
person t1
INNER JOIN person t2
WHERE
t1.id > t2.id
AND t1.email = t2.email;
数据脚本
create table `person` (
`id` int (11),
`email` varchar (120)
);
insert into `person` (`id`, `email`) values(‘1‘,‘bob@example.com‘);
insert into `person` (`id`, `email`) values(‘2‘,‘bob@example.com‘);
insert into `person` (`id`, `email`) values(‘3‘,‘john@example.com‘);
标签:重复 cat pre delete let mys 编写 -- 记录
原文地址:https://www.cnblogs.com/mengjianzhou/p/12795039.html