1. A language enabling the structure and instances of a database to be defined in a human-, and machine-readable form.
SQL contains DDL commands that can be used either interactively, or within programming language source code, to define databases and their components, e.g. CREATE and DROP.
See also Data manipulation language (DML).
2. A specification language for databases, based on the entity-relationship model. It is used in the Eli compiler-compiler to manage type definitions.
["DDL Reference Manual", ECE Dept U Colorado, 1991].