SQL, short for Structured Query Language, is the standard language for defining, querying and changing data in a relational database. It is declarative, meaning you describe the result and the database decides how to get it. MySQL, PostgreSQL and SQL Server are engines that implement SQL, each with its own extensions.
Its statements fall into four groups:
Data Definition Language (DDL) defines structure with CREATE, ALTER and DROP. TRUNCATE counts as DDL too.
Data Manipulation Language (DML) reads data with SELECT and changes it with INSERT, UPDATE and DELETE.
Data Control Language (DCL) controls access permissions with GRANT and REVOKE.
Transaction Control Language (TCL) manages transactions with COMMIT, ROLLBACK and SAVEPOINT.
Rewriting in plainer words…
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