4. Explain the role of transactions in database operations. How can you use the COMMIT and ROLLBACK statements to manage transactions effectively?

Transactions in database operations play a crucial role in ensuring data integrity and consistency. A transaction is a single logical unit of work that accesses and possibly modifies the contents of a database. Transactions in a database environment have two main purposes:

1. To provide reliable units of work that allow correct recovery from failures and keep a database consistent even in cases of system failure, when execution stops (completely or partially) and many operations upon a database remain uncompleted, with unclear status.

2. To provide isolation between programs accessing a database concurrently. If this isolation is not provided, the program's outcome are possibly erroneous.

The COMMIT and ROLLBACK SQL statements are used to manage transactions effectively.

COMMIT Statement: The COMMIT command is used to permanently save any transaction into the database. When we use any DML command like INSERT, UPDATE or DELETE, the changes made by these commands are not permanent, until the current session is closed, the changes made by these commands can be rolled back. To avoid that, we use the COMMIT command to mark the changes as permanent.

ROLLBACK Statement: The ROLLBACK command is the transactional command used to undo transactions that have not already been saved to the database. The ROLLBACK command can only be used to undo transactions since the last COMMIT or ROLLBACK command was issued.

In summary, transactions are vital in maintaining the integrity of data in a database. The COMMIT and ROLLBACK commands are used to manage these transactions effectively, ensuring that all database operations are successful and any unsuccessful operations do not affect the integrity of the data.