6.2.3 Relational Database Objects

This object-oriented interface is deprecated for typical database applications; Using Databases provides an application programmer interface which is easier to understand and use.

Function: make-relational-system base-table-implementation

Returns a procedure implementing a relational database using the base-table-implementation.

All of the operations of a base table implementation are accessed through a procedure defined by requireing that implementation. Similarly, all of the operations of the relational database implementation are accessed through the procedure returned by make-relational-system. For instance, a new relational database could be created from the procedure returned by make-relational-system by:

(require 'alist-table)
(define relational-alist-system
        (make-relational-system alist-table))
(define create-alist-database
        (relational-alist-system 'create-database))
(define my-database
        (create-alist-database "mydata.db"))

What follows are the descriptions of the methods available from relational system returned by a call to make-relational-system.

Operation on relational-system: create-database filename

Returns an open, nearly empty relational database associated with filename. The only tables defined are the system catalog and domain table. Calling the close-database method on this database and possibly other operations will cause filename to be written to. If filename is #f a temporary, non-disk based database will be created if such can be supported by the underlying base table implelentation. If the database cannot be created as specified #f is returned. For the fields and layout of descriptor tables, Catalog Representation

Operation on relational-system: open-database filename mutable?

Returns an open relational database associated with filename. If mutable? is #t, this database will have methods capable of effecting change to the database. If mutable? is #f, only methods for inquiring the database will be available. Calling the close-database (and possibly other) method on a mutable? database will cause filename to be written to. If the database cannot be opened as specified #f is returned.