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The Data Dictionary is the main Gembase tool used to interact with the underlying database engine. It has been designed to provide a consistent appearance on different database engines. A set of utilities allow the data structures required for any application to be built, and by defining the rules in a generalised way, Gembase's Platform Independence is provided.
The content of the Data Dictionary is a generalised set of classifications for data. Tables are used to store information which is broken down into fields, and fields are classified as different datatypes. Indexes are used to specify uniqueness, and along with domains, they are used to specify relationships between different tables. Parameters are used to store common and user-level information, or controls. Triggers allow events to be detected and actions automatically be taken. In this way, much of the complexity of the system is defined in the Data Dictionary whilst remaining free of database engine specifics.
This information is not the same as that used in the applications created with Gembase, it has been called Metadata, and a special set of Gembase commands are available to automatically enter this information into a database. (Well, it would be rather time consuming to enter it all manually every time!). Gembase records information on the state of the database, and a history of changes. The content of the Data Dictionary can also be manipulated with a set of Gembase commands. These commands manipulate what is referred to as Metadata.
Because the manipulation of Metadata can be carried out by the Gembase programming language, reports on the content of the database, can, and have, been produced in Gembase. In fact, whenever you create one of the reports on the content of your database, or build an update to apply to another database, you are running a Gembase program.
Reporting on the Metadata using Gembase programs is easy, but under no circumstances should the contents of the internal tables be altered directly. Only the Gembase commands provided to change the database should be used when modifying metadata.
In building this site, we intend to provide some utilities to improve on the standard set of data that can be extracted from the database. If you have any utilities you have developed for your personal use, please feel free to post them in the forum. However, please ensure you comply with the policies of your organisation in posting these. Before including them in the main part of this site, we reserve the right to adjust them to our coding standards.
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This page last updated on 28th February 1999.