next up previous contents index
Next: Relational data model Up: Data model Previous: Hierarchical data model

Network data model

In the network data model record types are organised in a directed graph structure. A record type may have zero or more predecessor and successor record types. As in the hierarchical data model, the information on an entity is held in records. Unlike fields in the hierarchical data model, the fields of a record in the network data model may have multiple values.

A set type describes a 1:N relationship between two record types. Set types have names to distinguish the relationships of a record type. Since a record type may be linked to any other record type, complex relationships, e.g. N:M relationships, may be represented.

Access to record types is possible via special ``entry point'' record types from which dependent record types can be reached through navigation.


EAGLES SWLG SoftEdition, May 1997. Get the book...