Calculate Age or Birthday

CREATE or replace FUNCTION CalculateAge(m_birthday date, m_datetoday date)
RETURNS INTEGER
AS
$$
BEGIN

RETURN

(
select
(
CASE
WHEN dateadd('y', datediff ('y', m_birthday, m_datetoday), m_birthday) > m_datetoday
THEN datediff ('y', m_birthday, m_datetoday) - 1
ELSE datediff ('y', m_birthday, m_datetoday)
END)

);

END;
$$ language 'plpgsql';

-- see my previous post on dateadd and datediff