mysql stored function parameter

Question

I have just started to create a stored function this is my first time so I am having a few problems. Currently I call the function using SELECT test(); (test is

Answer 1

Use:

DROP FUNCTION IF EXISTS `example`.`test` $$
CREATE FUNCTION `example`.`test` (param INT) RETURNS VARCHAR(32)
BEGIN

  DECLARE new_username VARCHAR(32);

    SELECT `username`
      INTO new_username
      FROM `users`
     WHERE `ID` = param;

    RETURN COALESCE(new_username, 'Username not found');

END $$

Mind that the VARCHAR length of the RETURN value matches the variable, which should match the column length you want to return.