2. (a) Draw an ER diagram for a database that stores tennis players. - For each player, we store his name, date of birth, country and ranking. - Each player plays matches with one or more other players. - However, each player plays only one match with one particular opponent. - For each match played between two players, we store the name of stadium and the score. - For each player, we also store his ideal player. Each player has at most one ideal player. (b) Convert the above ER--?diagram into a relational model.