What Is The Full Form Of TCL?
The full form of TCL is Transaction Control Language.
TCL commands are basically used for managing and controlling the transactions in a database to maintain consistency. And it also helps a user manage all the changes made by the DML commands for maintaining its transactions. TCL lets the statements get grouped into logical transactions.
A set of SQL statements executed on the information and data stored in the Database Management System (DBMS) is known as a transaction. Any transaction, when made, happens temporarily in the DB (database). A user needs TCL commands to make these alterations/changes permanent. The DDL command and DML command also assist a user in managing some modifications made by DML statements to the data in a table.
TCL Commands
The TCL commands are as follows:
- COMMIT
- ROLLBACK
- SAVEPOINT
Uses of TCL Commands
1. COMMIT
This command helps a user to save a given transaction into the DB permanently. When using a DML command like DELETE, UPDATE, or INSERT, the alterations made are not permanent until one closes the current session. Meaning, the changes can roll back if one doesn’t store data permanently. Thus, to avoid it and be on a safer side, we use the COMMIT command. It marks these changes as permanent.
The command syntax for COMMIT is COMMIT;
2. ROLLBACK
This command functions to restore the DB to the very committed state. One can also use it with the SAVEPOINT command when willing to jump to a save point in the ongoing transaction. Basically, it helps a user in getting or restoring the data to the last committed state/savepoint.
A user may deploy the UPDATE command to make a few changes in the DB, and they may realize that the alterations are unrequired. So, if, due to some reason, the inserted, updated, or deleted data is incorrect, the user can use the ROLLBACK command to rollback the data to the last committed state or any particular savepoint. Meaning, you can undo the changes if the user didn’t commit using the COMMIT command.
The command syntax for ROLLBACK is ROLLBACK TO savepoint_name;
3. SAVEPOINT
This command helps in saving a transaction temporarily so that a user can easily rollback to that point as and when required. So, you can name different data states in a table using the SAVEPOINT command and rollback to it as per the requirement using the ROLLBACK command.
The command syntax for SAVEPOINT is SAVEPOINT savepoint_name;
Advantages of TCL
- It is used in SQL (Structured Query Language), which is very interactive, portable, and works in multiple programs of PC, servers, and laptops.
- Users can easily access, edit, and save changes to the database.
- The coding required is not very complex. Even the new users can use it feasibly.
- The commands are easy to remember and handy.
Disadvantages of TCL
- The ROLLBACK command is of no use in the cases where a user commits using the COMMIT command.
- One has to create a savepoint in order to go back to it or else, a chunk of content changes will go in vain.
- Identifying savepoints may be confusing to new users.
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