SQL commands are categorized into several types based on their purpose. Here's a breakdown of the main types of SQL commands:

1. DDL (Data Definition Language)

• Commands that define or modify the structure of database objects (tables, indexes, schemas, etc.).

• Examples:

  • CREATE — Create tables, databases, views, etc.

  • ALTER — Modify existing database objects.

  • DROP — Delete tables, databases, or other objects.

  • TRUNCATE — Remove all rows from a table quickly.

  • RENAME — Rename database objects.

  • COMMENT — Add comments to database objects.

2. DML (Data Manipulation Language)

• Commands that manipulate data stored in the tables.

• Examples:

  • SELECT — Retrieve data from tables.

  • INSERT — Insert new rows into a table.

  • UPDATE — Modify existing data.

  • DELETE — Remove rows from a table.

  • MERGE — UPSERT operation (insert or update).

3. DCL (Data Control Language)

• Commands that control access and permissions to the database.

• Examples:

  • GRANT — Give users access privileges.

  • REVOKE — Remove access privileges.

4. TCL (Transaction Control Language)

• Commands that manage transactions to ensure data integrity.

• Examples:

  • COMMIT — Save transaction changes permanently.

  • ROLLBACK — Undo transaction changes.

  • SAVEPOINT — Set a point to which you can rollback.

  • SET TRANSACTION — Set transaction properties.

5. Other categories (less common)

• DQL (Data Query Language): Sometimes SELECT is classified separately as DQL because it only queries data.

• Utility commands: Database-specific commands for maintenance or optimization (e.g., ANALYZE, EXPLAIN).

Summary Table

If you'd like, I can explain any of these commands in detail or provide examples!