None
select a.player_id, a.event_date, sum(b.games_played) as games_played_so_far from Activity a, Activity b where a.player_id = b.player_id and a.event_date >= b.event_date group by a.player_id, a.event_date
None
select a.player_id, a.event_date, sum(b.games_played) as games_played_so_far from Activity a, Activity b where a.player_id = b.player_id and a.event_date >= b.event_date group by a.player_id, a.event_date