LeetCode：627. Swap Salary

最新推荐文章于 2024-03-13 18:09:18 发布

原创最新推荐文章于 2024-03-13 18:09:18 发布 · 314 阅读

0 ·

CC 4.0 BY-SA版权

Python 同时被 2 个专栏收录

36 篇文章

订阅专栏

LeetCode

20 篇文章

订阅专栏

本文介绍了一种使用SQL更新语句来实现表中特定字段值的互换方法，通过一个具体的例子展示了如何不借助临时表就能完成男女性别标识的交换。

题目：
Given a table salary, such as the one below, that has m=male and f=female values. Swap all f and m values (i.e., change all f values to m and vice versa) with a single update query and no intermediate temp table.
For example:

id	name	sex	salary
1	A	m	2500
2	B	f	1500
3	C	m	5500
4	D	f	500

After running your query, the above salary table should have the following rows:

id	name	sex	salary
1	A	f	2500
2	B	m	1500
3	C	f	5500
4	D	m	500

Answer：
思路：用到case，注意最后加END结束。

# Write your MySQL query statement below
UPDATE salary  set sex = CASE sex
    WHEN 'm' THEN
        'f'
    ELSE
        'm'
END;

附上salary表的sql创建语句：

create table if not exists salary(id int, name varchar(100), sex char(1), salary int);
Truncate table salary;
insert into salary (id, name, sex, salary) values ('1', 'A', 'm', '2500');
insert into salary (id, name, sex, salary) values ('2', 'B', 'f', '1500');
insert into salary (id, name, sex, salary) values ('3', 'C', 'm', '5500');
insert into salary (id, name, sex, salary) values ('4', 'D', 'f', '500');