Leetcode 627 Swap Salary

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 statement and no intermediate temp table.

Note that you must write a single update statement, DO NOT write any select statement for this problem.

Example:

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

After running your update statement, 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    |

CASE语句

不知道case之前完全没思路, 知道了之后就很简单了. case…when…then…else…end.

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

转化为ascii

答案来源于https://leetcode-cn.com/problems/swap-salary/solution/zi-mu-he-asciihu-zhuan-by-rachy/

很棒的解法!

update salary set sex = char(ascii('m') + ascii('f') - ascii(sex));