LeetCode——627. Swap Salary（數(shù)據(jù)庫,sql）

題目鏈接

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.

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

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

題解：

本來想用問號表達式，發(fā)現(xiàn)sql中沒有，用IF也不會，就參考了下幾種解法，不得不說異或確實不錯。

UPDATE salary SET sex = IF(sex = 'm', 'f', 'm')

UPDATE salary    SET sex  = (CASE WHEN sex = 'm'   THEN  'f'  ELSE 'm'   END)

UPDATE salary SET sex = IF(sex = 'm', 'f', 'm')