Final answer:
Implicit locks are automatically released after the user exits the system or when a COMMIT or ROLLBACK command is executed. These are managed by the DBMS to ensure transaction integrity and are released upon transaction completion.
Step-by-step explanation:
Implicit locks are automatically released when the user exits the system or executes a COMMIT or ROLLBACK command. Implicit locks are a type of lock that is automatically managed by the database management system (DBMS) to maintain the integrity of the database transactions. When a user starts a transaction and modifies data, the DBMS places these implicit locks to prevent other transactions from accessing the data in a conflicting way, thus ensuring the consistency of the database.
The use of implicit locks is crucial in multi-user database environments where numerous transactions can occur simultaneously. These locks ensure that only one transaction can write data to a particular item at a time, while still allowing multiple transactions to read the same data when appropriate, through shared locks. More restrictive locks, such as exclusive locks, are also employed to ensure data cannot be read nor written by other transactions until the current transaction is completed or undone. Once the user decides to finalize the transaction with COMMIT, which saves all changes, or ROLLBACK, which undoes them, the implicit locks are no longer necessary and are thus released.