Swap sex of employees

#
# Table: Salary
# +-------------+----------+
# | Column Name | Type     |
# +-------------+----------+
# | id          | int      |
# | name        | varchar  |
# | sex         | ENUM     |
# | salary      | int      |
# +-------------+----------+
# id is the primary key (column with unique values) for this table.
# The sex column is ENUM (category) value of type ('m', 'f').
# The table contains information about an employee.
# Write a solution 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 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'.
#

# Write your MySQL query statement below

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