What is DDL , DML , DCL & TCL

Welcome to the SQL Beginners Guide series’ latest article. We are about to discuss SQL Languages also known as categories of SQL Statements . We will discuss what is DDL , DML and other types and what they do . However , before we move forward. In case you need to check other articles.

Following are the most recent articles

  1. What is SQL ?
  2. MS SQL Installation Step By Step
  3. SQL Select Query
  4. Basic SQL Queries & Commands

Reason for referring you to the previous articles is very simple. This is a series and they are being composed in order . Therefore , this order will help you in developing a better understanding for SQL query development .

SQL commands have following categories

 

Types of SQL Statements/SQL Commands

  • DML  Data Manipulation Language
  • DDL   Data Definition Language
  • DCL   Data Control Language
  • TCL   Transaction Control Language

Let’s do it people , time to discuss them .

DML  ( Data Manipulation Language )

Remember , CRUD Operations ? The basic SQL queries we use to work with the data in table . It can be as simple as retrieving information from table  , inserting , deleting or update.

SELECT – Retrieves data from tables

INSERT – Inserts data into tables

UPDATE– Update data in tables.

DELETE – Delete data or objects

Previous article , has these SQL queries for practice. In case , you’re interested.

DDL ( Data Definition Language )

Statements that are used to change the state of database objects such as table , schema etc.

CREATE – Create the database objects

ALTER – Can you guess? Yes , Alter the already defined values. Can be datatypes of columns or names of the objects

DROP -Delete existing object from database

TRUNCATE – Also delete the existing from database but to the point that it cannot be restored because no log maintenance for this operation unlike others.

DCL  ( Data Control Language )

Statements that are used to manage and control the access of users on database objects

GRANT – allow user acces to read/write on certain database objects
REVOKE – removes user access from read/write permission on database objects.

TCL ( Transaction Control Language )

SQL Statements that allows 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.

In future , we are planning to write on Concurrency Control where you will see a good use of the TCL Statements. Therefore , my recommendation is to subscribe us and follow us for the latest articles.

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