2) Online Banking System ER Diagram:

                                    +-------------+
                                    |   Customer  |
                                    +-------------+
                                    | customer_id (PK)
                                    | name
                                    | email
                                    | address
                                    +-------------+
                                            |
                                            |
                                  +---------+---------+
                                  |                   |
                          +-------+-------+   +-------+-------+
                          |   Owns Account |   |    Account    |
                          |               |   +---------------+
                          +---------------+   | account_id (PK)|
                          | account_id (PK)|   | balance       |
                          | customer_id (FK)|  | type          |
                          | balance        |   | status        |
                          +---------------+   +---------------+
                                                |
                                                |
                                    +-----------+-----------+
                                    |                       |
                            +-------+-------+   +-----------+-------+
                            |   Performs    |   |    Transaction    |
                            +---------------+   +-------------------+
                            | transaction_id(PK)| transaction_id (PK)|
                            | account_id (FK)|   | account_id (FK)   |
                            | date          |   | type              |
                            | amount        |   | amount            |
                            +---------------+   +-------------------+