- Create a ER Diagram for Basketball Leagues. We can have various basketball leagues. Leagues have teams and teams have players. Name of the league is always unique, but the teams and players name may not be unique. However, a league cannot have multiple teams with same name and a team cannot have multiple players with same number. But multiple players may be possible in different teams with same number. Similarly, there can be multiple teams with same name in different leagues. - Hint: It will have weak entity sets and relationships