SQL Command Categories
SQL commands are grouped into four major categories depending on their functionality. They are as follows
Data Definition Language (DDL)
These SQL commands are used for creating, modifying, and dropping the structure of database objects. The commands are CREATE, ALTER, DROP, RENAME, and TRUNCATE.
Data Manipulation Language (DML)
These SQL commands are used for storing, retrieving, modifying, and deleting data. These commands are SELECT, INSERT, UPDATE, and DELETE.
Transaction Control Language (TCL)
These SQL commands are used for managing changes affecting the data. These commands are COMMIT, ROLLBACK, and SAVEPOINT.
Data Control Language (DCL)
These SQL commands are used for providing security to database objects. These commands are GRANT and REVOKE.
SQL is followed by unique set of rules and guidelines called Syntax. All the SQL statements start with any of the keywords like SELECT, INSERT, UPDATE, DELETE, ALTER, DROP, CREATE, USE, SHOW and the entire statements end with a semicolon (;). Important point to be noted is that SQL is case insensitive, which means SELECT and select have same meaning in SQL statements.
