SUM() window function to calculate the cumulative sum of games played.player_id to ensure the cumulative sum is calculated separately for each player.event_date in ascending order to ensure the games are summed in chronological order.player_id, event_date, and the calculated cumulative sum as games_played_so_far.erDiagram
Activity {
int player_id
int device_id
date event_date
int games_played
player_id event_date PK
}