DTL Overview
Data Transaction Language (DTL) commands are used to manage transactions in a database. They allow for the control and management of multiple operations, ensuring data integrity through commit and rollback mechanisms. Transactions help ensure that the database remains consistent, even in the event of errors or system failures.
Common DTL Commands
| Command | Description |
|---|---|
BEGIN TRANSACTION | Starts a new transaction explicitly. |
COMMIT | Saves all changes made by the current transaction to the database. |
ROLLBACK | Reverts all changes made by the current transaction. |
SAVEPOINT | Sets a point within a transaction to which a rollback can be performed. |
SET TRANSACTION | Sets the properties of the current transaction, such as isolation level. |
Purpose of DTL
DTL is used to ensure the integrity and consistency of the database by treating a set of operations as a single unit. If all operations succeed, changes are saved; otherwise, they are rolled back.
Characteristics of Transactions
- Transactions ensure atomicity, meaning all operations are completed successfully or none at all.
- They maintain consistency by ensuring the database remains in a valid state.
- They provide isolation to prevent interference between concurrent transactions.
- Durability ensures that changes made by committed transactions are permanent.