Check function parameter and return value : Function Returning « Procedure Function « MySQL Tutorial

1. MySQL Tutorial
2. Procedure Function
3. Function Returning

mysql>
mysql> delimiter $$
mysql>
mysql> CREATE FUNCTION myFunction(in_status CHAR(1))
    ->      RETURNS VARCHAR(20)
    -> BEGIN
    ->      IF in_status = 'O' THEN
    ->           RETURN('Overdue');
    ->      ELSEIF in_status = 'U' THEN
    ->           RETURN('Up to date');
    ->      ELSEIF in_status = 'N' THEN
    ->           RETURN('New');
    ->      END IF;
    -> END$$
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql> delimiter ;
mysql>
mysql> select myFunction('O');
+-----------------+
| myFunction('O') |
+-----------------+
| Overdue         |
+-----------------+
1 row in set (0.00 sec)

mysql>
mysql> select myFunction('U');
+-----------------+
| myFunction('U') |
+-----------------+
| Up to date      |
+-----------------+
1 row in set (0.00 sec)

mysql>
mysql> select myFunction('N');
+-----------------+
| myFunction('N') |
+-----------------+
| New             |
+-----------------+
1 row in set (0.00 sec)

mysql>
mysql>
mysql> drop function myFunction;
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql>