leetcode-627-Swap-Salary

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描述

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:

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| 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:

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

分析

注意是更新表，不是 SELECT，这个 CASE 的语法用得少，可以多看一下

解决方案(MySQL)

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

题目来源