The SQL commands are categorized into the following categories:
- DDL - Data Definition Language
- DML - Data Manipulation Language
- DQL - Data Query Language
- DCL - Data Control Language
- TCL - Transaction Control Language
Let's see each of them in detail.
DDL
- Queries like - CREATE, DROP, TRUNCATE, and ALTER fall into this category because they all manage the structure of DB Objects in some way.
- For eg: CREATE command creates the structure of a table, DROP command removes the table structure.
DML
- Queries like DELETE, UPDATE and INSERT fall into this category because they all manipulate the data in some way.
- For eg: the DELETE command removes data in a table, UPDATE command updates the data.
DQL
- The SELECT query falls into this category because it is used to query the database and get the output of the query.
- For eg: Using SELECT, we can ask any specific question to a DB and get answers.
DCL
- Queries like GRANT, and REVOKE fall into this category because they're used to control access to the DB.
- For eg: GRANT will assign permission to a user on a DB Object and REVOKE will remove the permission.
TCL
- Queries like ROLLBACK, COMMIT & SAVE POINT fall into this category as they're used to manage transactions in the database.
- For eg: the COMMIT command commits the transaction and the ROLLBACK command rollback all changes done to a DB when a transaction fails.
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