Relational access can, for example, take place via the SQL interface of DRIVE V2.1 (see the “DRIVE/WINDOWS (BS2000)“ manuals).
To aid the SQL user when working in this way, BPSQLSIA can be used to print out a relational representation of existing UDS/SQL data structures that have been defined in accordance with the CODASYL model. In the following sections, this relational description of the data structures will be called relational schema information.
The CODASYL schema remains unchanged, however, and can continue to be used by CODASYL applications.
The relational schema information includes all the information needed, such as table names and field definitions, to permit the SQL user to work with a CODASYL database on a relational basis. It also indicates whether an existing CODASYL subschema can be processed on a completely relational basis or whether such access is limited.
BPSQLSIA generates separate relational schema information for each CODASYL subschema.