case

Description

Syntax:

CASE expression
    WHEN condition1 THEN result1
    [WHEN condition2 THEN result2]
    ...
    [WHEN conditionN THEN resultN]
    [ELSE result]
END

CASE WHEN condition1 THEN result1
    [WHEN condition2 THEN result2]
    ...
    [WHEN conditionN THEN resultN]
    [ELSE result]
END

This function compares the expression with multiple possible values, and returns the corresponding results when they match.

Example

mysql> select user_id, case user_id when 1 then 'user_id = 1' when 2 then 'user_id = 2' else 'user_id not exist' end test_case from test;
+---------+-------------+
| user_id | test_case   |
+---------+-------------+
| 1       | user_id = 1 |
| 2       | user_id = 2 |
+---------+-------------+
 
mysql> select user_id, case when user_id = 1 then 'user_id = 1' when user_id = 2 then 'user_id = 2' else 'user_id not exist' end test_case from test;
+---------+-------------+
| user_id | test_case   |
+---------+-------------+
| 1       | user_id = 1 |
| 2       | user_id = 2 |
+---------+-------------+

Keywords

CASE

bitxor coalesce