A Data Manipulation Language (DML) is a family of computer languages used by computer programs and/or database users to insert, delete and update data in a database. Read-only querying, i.e. SELECT, of this data may be considered to be either part of DML or outside it, depending on the context.
A Data Definition Language or Data Description Language (DDL) is a computer language for defining data structures. The term DDL was first introduced in relation to the Codasyl database model, where the schema of the database was written in a Data Description Language describing the records, fields, and “sets” making up the user Data Model. Later it was used to refer to a subset of SQL, but is now used in a generic sense to refer to any formal language for describing data or information structures, like XML schemas.
A Data Control Language (DCL) is a computer language and a subset of SQL, used to control access to data in a database.
