What is Data Definition Language (DDL) in SQL?

Data Definition Language (DDL) is a subset of SQL that provides commands to create, modify, and delete database objects such as tables, views, and indexes. It also includes commands to manage user access privileges. Common DDL commands include CREATE TABLE, DROP TABLE, ALTER TABLE, CREATE VIEW, CREATE INDEX, GRANT, and REVOKE.

What is the difference between DDL and DML in SQL?

DDL (Data Definition Language) defines the structure of the database — creating, altering, and dropping tables, views, and indexes. DML (Data Manipulation Language) operates on the data within those structures using commands like SELECT, INSERT, UPDATE, and DELETE.

What is the difference between DROP TABLE and TRUNCATE TABLE?

DROP TABLE removes the entire table including its structure and all data. TRUNCATE TABLE removes all rows from the table but keeps the table structure intact, so you can insert new data afterward. TRUNCATE is generally faster than DELETE for removing all rows.

What are GRANT and REVOKE in SQL DDL?

GRANT gives a user permission to perform specific actions on database objects (e.g., SELECT, INSERT, UPDATE). REVOKE removes those permissions. Both are part of DDL and are used to control access and enforce security in a database.

Data Definition Language - DDL

SQL > Data Definition Language - DDL

Data Definition Language (DDL) is a part of SQL that is used to create, modify, and delete database objects such as table, view, and index, and to manage access privileges to these objects. Below are the most common DDL commands:

SQL Data Definition Language (DDL) covers commands that define and manage the structure of your database — including creating tables, managing indexes and views, dropping objects, and controlling access privileges via GRANT and REVOKE.

Frequently Asked Questions

What is Data Definition Language (DDL) in SQL?: DDL is a subset of SQL focused on defining and managing database structure. It includes commands to create (CREATE TABLE, CREATE VIEW, CREATE INDEX), modify (ALTER TABLE), and delete (DROP TABLE, DROP DATABASE) database objects, as well as manage access privileges (GRANT, REVOKE).
What is the difference between DDL and DML in SQL?: DDL defines the database structure — it creates, alters, and drops tables, views, and indexes. DML (Data Manipulation Language) works with the data stored in those structures, using SELECT, INSERT, UPDATE, and DELETE to query and modify rows.
What is the difference between DROP TABLE and TRUNCATE TABLE?: DROP TABLE permanently removes both the table structure and all its data. TRUNCATE TABLE deletes all rows but preserves the table structure so new data can be inserted. TRUNCATE is typically faster than DELETE for clearing all rows since it doesn't log individual row deletions.
What are GRANT and REVOKE in SQL?: GRANT assigns specific privileges (such as SELECT, INSERT, UPDATE, DELETE) on database objects to a user or role. REVOKE removes those privileges. Together they implement database security and control who can access or modify data.

Next: SQL CREATE TABLE

This page was last updated on March 19, 2026.

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Data Definition Language - DDL

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