The DP4 Relational Database Management System (RDBMS) includes tools for implementing, distributing and maintaining relational databases.
The DP4 RDBMS supports data independence to shield programs that access DP4 databases from the physical storage details of the data. This means that you can modify the database structure without modifying the application, if the logic of the application is not affected.
The DP4 RDBMS supports operating-system independence. You can develop and test a database on one operating system and then port it to another and not incur extra development time.
In DP4's implementation of the relational database model, entities are represented as tables, instances of entities are represented as records and attributes of entities are represented as fields. You do not need to set up the relationships between tables explicitly; DP4 automatically derives the structure of the database from an analysis of its tables. For example, a parent-child link is derived where you include the primary key of the parent table in the child table.
The DP4 RDBMS supports referential integrity, which allows you to set rules that define how a change on one table affects related tables. This can help to reduce application development time.
The DP4 utilities carry out the tasks you want on the database, depending on your responses to a series of questions, in most cases requiring yes/no answers or option selection from menus. Default responses are suggested where appropriate and context-sensitive help is always at hand.
The DP4 RDBMS provides special facilities for the development of applications in multiple international languages. A multi-language application supports the differing language requirements of its users at runtime.
Significant among the security and integrity features offered by the DP4 RDBMS are:
Automatic maintenance of a transaction log and roll-back log for database recovery.
Contention control and record locking in multi-user systems.
Enforced database backup and integrity checking schemes.
Together these facilities allow you quickly to deliver powerful, robust, DP4 databases upon which applications can be built with confidence for client/server environments.