Network Database Model

• The network database model expands on the hierarchical model by providing multiple paths among segments (i.e., more than one parent/child relationship)

• The network model was standardized as the  CODASYL DBTG model

• The network model is for all practical purposes obsolete

• Although supporting multiple paths in the data structure eliminates some of the inflexibility of the hierarchical model, the network model is not very practical

• The network model only supports simple network relationship that are implemented as 'chains' connecting individual records

• With no restrictions on the number of relations, the database design can become overwhelmingly complex 

• The relational model provides the same flexibility offered by the network model but is much easier to work with

At its core the very basic modeling construct is the set construct. This set consists of an owner record, the set name, and the member record. Now, this 'member' can play this role in more than one set at the same time; therefore this member can have multiple parents. Also an owner type can be owner or member in one or more other set constructs. This means the network model allows multiple paths between segments. This is a valuable improvement on relationships, but could make a database structure very complex.

Actually, by working through the relevant set structures. A user need not work down his way through root tables, but can retrieve data by starting at any node and working through the related sets. This provides fast data access and allows the creation of more complex queries than could be created with the hierarchical model. But, once again, the disadvantage is that the user must be familiar with the physical data structure. Also, it is not easy to change the database structure without affecting the application, because if you change a set structure you need to change all references to that structure within the application.