Goal: Count of Patient days in a month Feb. by patient account
Conditions:
admit >02/01/02 and discharge >02/28/02, then 02/28/02-admit
admit >02/01/02 and discharge <02/28/02, then discharge -admit
admit< 02/01/02 and discharge >02/28/02, then 02/28/02-02/01/02
admit < 02/01/02 and...