Define Transaction Control Language (TCL).
Definition should include the following:
- TRANSACTION—a logical unit of statements that must be executed together
- ROLLBACK—will clear the buffer without saving changes (implicit for all DDL or DCL statements)
- SAVEPOINT—creates a chronological marker that can be named in a rollback
- COMMIT—ends the transaction and makes changes in the buffer permanent
- Read consistency—guarantees a consistent view of the data at all times