DDL ("Data Definition Language") is a set of statements the user executes in order to create a new database. In RDM 15.1, standard SQL DDL statements are used for these purposes.

RDM 15.1 provides two methods to create a database.

The first method is to save the DDL statements in a file (called "schema definition file") and compile it using the rdm-compile or rdm-create tool. rdm-compile generates files that can be embedded into an application. rdm-create creates a database that can be accessed directly by an application.

The second method is to execute DDL statements on the fly through SQL. RDM 15.1 provides a command-line interactive tool named rdm-sql. The user can type in DDL statements directly at the rdm-sql command prompt, or feed a file that contains DDL statements into the tool.

Here is an example of a simple schema definition file.

CREATE TABLE maker(    maker_id INTEGER PRIMARY KEY,    maker_name CHAR (20));CREATE TABLE product(    product_id CHAR (5) PRIMARY KEY,    product_name CHAR (50),    maker_id INTEGER REFERENCES maker (maker_id));

Learn more about creating a database in the following "Defining a Database" section.