CREATE FUNCTION ufn_get_salary_level(`parameter` DOUBLE(19,4))
RETURNS VARCHAR(8)
BEGIN
    DECLARE result VARCHAR(8);
    CASE
        WHEN `parameter`< 30000
            THEN SET `result` = 'Low';
        WHEN `parameter`>= 30000 AND `parameter` <= 50000
            THEN SET `result` = 'Average';
        ELSE SET `result` = 'High';
    END CASE;
    RETURN `result`;
END