Difference between DML and TCL

Prerequisite – DDL, DML, TCL and DCL
1. Data Manipulation Language (DML) :
DML is used to manipulate data in the database. For example, insert, update and delete instructions in SQL.

2. Transaction Control Language (TCL) :
TCL deals with the transactions within the database.



Difference between DML and TCL :

S. no. Category DML TCL
1. Full Form DML stands for Data Manipulation Language. TCL stands for Transaction Control Language.
2. Definition DML 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. Classification Data Modification Language is further classified into Procedural and Non-Procedural DML. Transaction Control Language doesn’t have any further classifications.
4. DBMS feature exhibited It exhibits the feature of easy maintenance (of files). It exhibits the feature of Atomicity.
5. Use in Transactions DML cannot be used for database transactions. TCL is used for handling database transactions.
6. Order DML 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 files It does not use Log files. It uses log files to keep a record of all transactions.
8. Commands Frequently 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 TRNSACTION.
9. Handled by DML 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. Locking It uses Locks for concurrency control. It does not use Locks.
11. WHERE clause Most DML statements have WHERE clause to filter them. TCL does not need WHERE clause.
12. Data Access Paths DML can be used to explain access paths to data. TCL cannot explain data access paths.
13. Call a subprogram It is used to call PL/SQL or Java subprogram. It is not used to call subprograms.
14. Merge operation We can perform Merge operation using DML. TCL cannot perform Merge operations.
15. Trigger Triggers are fired after DML statements. TCL is not used for triggers.
16. Example Example 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;

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