9) Railway Reservation System ER Diagram:

                                    +-------------+
                                    |   Passenger |
                                    +-------------+
                                    | passenger_id (PK)
                                    | name
                                    | age
                                    | gender
                                    +-------------+
                                            |
                                            |
                                  +---------+---------+
                                  |                   |
                          +-------+-------+   +-------+-------+
                          |     Books     |   |    Train      |
                          |     Ticket    |   +---------------+
                          +---------------+   | train_id (PK) |
                          | ticket_id (PK)|   | name          |
                          | passenger_id (FK)| | source        |
                          | train_id (FK) |   | destination   |
                          | booking_date  |   | departure_time|
                          | status        |   | arrival_time  |
                          +---------------+   | fare          |
                                              +---------------+