Beginner

8. SQL Command Categories

Understand the major categories of SQL commands and what each category is designed to do.

📘 Lesson 8 of 728 ⏱ 7 min 🎯 Beginner

SQL commands are commonly organized into categories based on their purpose. DDL stands for Data Definition Language and is used to define database structures. DML stands for Data Manipulation Language and is used to modify data. DQL, commonly used to describe data retrieval commands, includes SELECT. DCL stands for Data Control Language and is used to manage permissions. TCL stands for Transaction Control Language and is used to manage transactions.

Knowing SQL command categories gives you a clear mental model of the language. Instead of memorizing commands randomly, you can understand whether a command is being used to create database objects, modify data, retrieve information, control permissions, or manage transactions.

CREATE TABLE is commonly classified as DDL. INSERT, UPDATE, and DELETE are DML commands. SELECT is commonly classified as DQL. GRANT and REVOKE are DCL commands, while COMMIT and ROLLBACK are TCL commands.

SQL 
CREATE TABLE Employees (
    EmployeeID INT,
    EmployeeName VARCHAR(100),
    Salary DECIMAL(12,2)
);

Database developers and administrators use different SQL command categories depending on the task. A developer may use DML to update application data, while a DBA may use DDL and DCL to manage database structures and permissions.

  • DDL defines database structures.
  • DML modifies stored data.
  • DQL retrieves data.
  • DCL manages permissions.
  • TCL manages transactions.
  • Understanding categories makes SQL easier to learn.
What are the main SQL command categories?

The commonly used categories are DDL, DML, DQL, DCL, and TCL.

Which category does SELECT belong to?

SELECT is commonly categorized as DQL, or Data Query Language.

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