627 Swap Salary

Description

Table: Salary

• 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.

Problem Statement

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:

Output:

Explanation:

• (1, A) and (3, C) were changed from ’m’ to ‘f’.
• (2, B) and (4, D) were changed from ‘f’ to ’m’.

Solution

The problem is asking us to swap male and females in a single statement. This can be done using IF and CASE WHEN statements.

1UPDATE Salary
2    SET sex = CASE WHEN sex = 'm' THEN 'f' ELSE 'm' END;

Using IF statement, it will look even simpler.

1UPDATE Salary
2    SET sex = IF(sex = 'm', 'f', 'm');