Data Definition Language (DDL)

A (DDL) is a language for specifying the database schema and other properties of the data.

The part of a DBMS interface enabling clients to manage metadata, that is data about data. It is stored in a data dictionary allowing the Database System to consult before modifying the actual data or reading.

Metadata includes:
▶ a logical schema $\to$ the logical metadata defining how data is understood ▶ a physical schema $\to$ the physical metadata defining how data is encoded ▶ external schemata $\to$ comprised of subsets of the logical schema

SQL Data Definition Language

SQL provides a rich DDL that allows one to define tables with data types and integrity constraints.

Related

• Data Manipulation Language