Problem 627: swap salary

problems/0627-swap-salary/main.sql

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+UPDATE Salary SET sex = CASE WHEN sex = "f" THEN "m" ELSE "f" END;

problems/0627-swap-salary/readme.md

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+# Swap salary
+
+[Leetcode](https://leetcode.com/problems/swap-salary/)
+
+Table: `Salary`
+
+```
++-------------+----------+
+| Column Name | Type     |
++-------------+----------+
+| id          | int      |
+| name        | varchar  |
+| sex         | ENUM     |
+| salary      | int      |
++-------------+----------+
+```
+
+Id is the primary key for this table.
+The sex column is ENUM value of type ('m', 'f').
+The table contains information about an employee.
+
+Write an SQL query to 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 temporary tables.
+
+Note that you must write a single update statement, do not write any select statement for this problem.
+
+The query result format is in the following example.
+ 
+## Example 1:
+
+```
+Input: 
+Salary table:
++----+------+-----+--------+
+| id | name | sex | salary |
++----+------+-----+--------+
+| 1  | A    | m   | 2500   |
+| 2  | B    | f   | 1500   |
+| 3  | C    | m   | 5500   |
+| 4  | D    | f   | 500    |
++----+------+-----+--------+
+Output: 
++----+------+-----+--------+
+| id | name | sex | salary |
++----+------+-----+--------+
+| 1  | A    | f   | 2500   |
+| 2  | B    | m   | 1500   |
+| 3  | C    | f   | 5500   |
+| 4  | D    | m   | 500    |
++----+------+-----+--------+
+```
+
+Explanation: 
+(1, A) and (3, C) were changed from 'm' to 'f'.
+(2, B) and (4, D) were changed from 'f' to 'm'.