EXTRACT(year FROM age(end_date,start_date))*12 + EXTRACT(month FROM age(end_date,start_date))
SELECT
AGE('2012-03-05', '2010-04-01'),
DATE_PART('year', AGE('2012-03-05', '2010-04-01')) AS years,
DATE_PART('month', AGE('2012-03-05', '2010-04-01')) AS months,
DATE_PART('day', AGE('2012-03-05', '2010-04-01')) AS days;