Understanding SQL aggregation efficiency

How would the first query compete in terms of performance against the second alternative: Query 1: select count(*) page_views, count(distinct(session_id)) sessions, (count(*) / count(distinct(session_id))) pages_per_session from page_views_table Query 2: select page_views, sessions, (page_views / sessions) pages_per_session from ( select count(*) page_views, count(distinct(session_id)) sessions from page_views_table ) I basically want to know if by using the first query, the database would need to calculate page_views (count(*)) and sessions (count(distinct(session_id))) twice in order to get the pages_per_session field, because if that's the case then the second query should be faster. So is the second query in fact the better choice?