MULTIPLE-TO-MULTIPLE RELATIONSHIP N : M always becomes a table players 1 N match_participants N 1 matches player_id Primary Key match_id + player_id PK match_id PK What else is useful to include in the relationship table? match_participants match_id FK -> matches player_id FK -> players team 1 or 2 <- attribute of the relationship itself kills deaths assists damage <- statistics for this match The relationship table is not a "technical" table. It contains attributes that do not belong to a player or a match, but rather to a combination of the two.