The database meta-schema file

The .4dbx file is the database meta-schema file for generated applications.

The database meta-schema (.4dbx) file contains the information about the tables, columns, and relations of the relational database that is needed by your application. It is used to create items in your Business Application diagram (4ba).

The database meta-schema file handles CRUD operations for the generated application. For each table with a primary key in the database schema, the application generator creates its database CRUD operations (INSERT, SELECT, UPDATE, and DELETE database statements respectively).

You must have access set up for the database that the application will use.

Constraints management

The Application Generator creates functions to manage the database schema constraints. These constraints are checked during the CRUD operations for each table:
  • uniqueness check for its primary key (only if a primary key exists)
  • uniqueness check for each unique constraint (only if a primary key exists)
  • for one column, the not null constraint is checked
  • foreign key existence is checked

SERIAL management

Primary keys you define as SERIAL are managed by the BAM using a table named seqreg in the meta-schema (4dbx). BAM uses this table to provide a sequence of unique integer numbers for SERIAL columns keys.