VOOZH about

URL: https://www.geeksforgeeks.org/dbms/difference-between-dml-and-tcl/

⇱ Difference Between DML and TCL - GeeksforGeeks

  • Courses
  • Tutorials
  • Interview Prep

Difference Between DML and TCL

Last Updated : 15 Jul, 2025

Data Manipulation Language (DML) and Transaction Control Language (TCL) are critical subsets of SQL (Structured Query Language). Both play essential roles in managing and controlling data in a database, but they serve different purposes. In this article, we will explore about the Difference between DML and TCL in detail.

Prerequisite:

DDL, DML, TCL and DCL

What is Data Manipulation Language (DML) ?

DML is used to manipulate data in the database. For example, insert, update and delete instructions in SQL. 

Key DML Commands:

  • SELECT – Retrieves data from the database.
  • INSERT – Adds new data into the database.
  • UPDATE – Modifies existing data.
  • DELETE – Removes data from the database.

Advantages of DML:

  • Easy Data Modification: DML commands allow users to easily modify and retrieve data as needed.
  • Flexible Queries: You can use the SELECT statement with various conditions to retrieve specific records.
  • Data Interaction: Allows for interaction with the database without directly altering the database schema.

Disadvantages of DML:

  • No Transaction Control: While DML handles data manipulation, it does not provide control over transactions like commit or rollback.
  • Potential Data Loss: Incorrect use of DELETE or UPDATE can lead to unintentional loss of data if not used cautiously.

What is Transaction Control Language (TCL) ?

TCL deals with the transactions within the database. 

Key TCL Commands

  • COMMIT – Saves the changes made during a transaction.
  • ROLLBACK – Reverts the database to its previous state if an error occurs.
  • SAVEPOINT – Creates points within transactions to which you can rollback.
  • SET TRANSACTION – Defines properties for a new transaction.

Advantages of TCL

  • Transaction Safety: Ensures that database transactions are executed correctly and consistently.
  • Error Handling: In case of any failure, ROLLBACK helps prevent partial or incorrect data being saved in the database.
  • Data Consistency: Maintains the integrity of data across multiple operations.

Disadvantages of TCL

  • Complexity: Managing multiple transactions and ensuring proper usage of commit and rollback can become complex in large systems.
  • No Data Interaction: TCL doesn't handle direct data manipulation, so it relies on DML or other SQL commands for modifying data.

Difference between DML and TCL

S. no.CategoryDMLTCL
1.Full FormDML stands for Data Manipulation Language.TCL stands for Transaction Control Language.
2.DefinitionDML stands for Data Manipulation Language and is used to manipulate data in the database by performing insertion, updating and deletion operations.Transaction Control Language (TCL) consists of commands that deal with the transactions within databases. 
3.ClassificationData Modification Language is further classified into Procedural and Non-Procedural DML.Transaction Control Language doesn't have any further classifications.
4.DBMS feature exhibitedIt exhibits the feature of easy maintenance (of files).It exhibits the feature of Atomicity.
5.Use in TransactionsDML cannot be used for database transactions.TCL is used for handling database transactions.
6.OrderDML statements are usually written before TCL statements in a Query.TCL statements are usually written after DML statements in a Query.
7.Use of Log filesIt does not use Log files.It uses log files to keep a record of all transactions.
8.CommandsFrequently used commands present in DML are: UPDATE, INSERT, MERGE, SELECT, DELETE, CALL, EXPLAIN PLAN, LOCK TABLE.Frequently used commands present in TCL are: COMMIT, ROLLBACK, SAVEPOINT, SET TRANSACTION.
9.Handled byDML is handled by the Query Compiler and Query Optimizer part of the DBMS architecture.TCL is handled by the Transaction Manager and Recovery Manager.
10.LockingIt uses Locks for concurrency control.It does not use Locks.
11.WHERE clauseMost DML statements have WHERE clause to filter them.TCL does not need WHERE clause.
12.Data Access PathsDML can be used to explain access paths to data.TCL cannot explain data access paths.
13.Call a subprogramIt is used to call PL/SQL or Java subprogram.It is not used to call subprograms.
14.Merge operationWe can perform Merge operation using DML.TCL cannot perform Merge operations.
15.TriggerTriggers are fired after DML statements.TCL is not used for triggers.
16.ExampleExample of SQL query that finds the names of all instructors in the History department : 
SELECT name 
FROM instructor 
WHERE dept_name = 'History'; 
We will use commit command to save the table record permanently. Incase we want to update the name Jolly to sherlock and save it permanently, we would use the following, 
UPDATE STUDENT 
SET NAME = ‘Sherlock’ 
WHERE NAME = ‘Jolly’; 

COMMIT; 
ROLLBACK;

What is the main difference between DML and TCL?

The main difference is that DML deals with data manipulation (inserting, updating, deleting data), while TCL controls the transactions (commit, rollback) that affect the state of the database.

Can we use DML commands without TCL?

Yes, DML commands can be used without TCL, but using TCL commands such as COMMIT or ROLLBACK ensures that changes made by DML commands are either saved or reverted consistently.

What happens if we don’t use TCL commands after a DML operation?

If you don't use TCL commands, the changes made by DML might not be saved permanently or could lead to inconsistent database states in the event of a failure.

Which is more important, DML or TCL?

Both are equally important. DML allows you to interact with and manipulate data, while TCL ensures those interactions happen within a controlled and safe transaction.

Comment
Article Tags:
Article Tags:

Explore