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DML, DDL, DCL and TCL Statements in SQL with Examples

SQL language is divided into four types of primary language statements: DML, DDL, DCL and TCL. Using these statements, we can define the structure of a database by creating and altering database objects, and we can manipulate data in a table through updates or deletions. We also can control which user can read/write data or manage transactions to create a single unit of work.

The four main categories of SQL statements are as follows:

1. DML (Data Manipulation Language)
2. DDL (Data Definition Language)
3. DCL (Data Control Language)
4. TCL (Transaction Control Language)


DML (Data Manipulation Language)

DML statements affect records in a table. These are basic operations we perform on data such as selecting a few records from a table, inserting new records, deleting unnecessary records, and updating/modifying existing records.

DML statements include the following:

SELECT – select records from a table
INSERT – insert new records
UPDATE – update/Modify existing records
DELETE – delete existing records

DDL (Data Definition Language)

DDL statements are used to alter/modify a database or table structure and schema. These statements handle the design and storage of database objects.

CREATE – create a new Table, database, schema
ALTER – alter existing table, column description
DROP – delete existing objects from database

DCL (Data Control Language)

DCL statements control the level of access that users have on database objects.

GRANT – allows users to read/write on certain database objects
REVOKE – keeps users from read/write permission on database objects

TCL (Transaction Control Language)

TCL statements allow you to control and manage transactions to maintain the integrity of data within SQL statements.

BEGIN Transaction – opens a transaction
COMMIT Transaction – commits a transaction
ROLLBACK Transaction – ROLLBACK a transaction in case of any error

Vishwanath Dalvi
Vishwanath Dalvi
Vishwanath Dalvi is a gifted engineer and tech enthusiast. He enjoys music, magic, movies, and gaming. When not hacking around or supporting the open source community, he is trying to overcome his phobia of dogs.


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