Network Model in DBMS
Network model in DBMS
- In 1970s CODASYL (conference on data system language) introduced a
network modelwhich is an extension to the hierarchical model but the difference is that the network model uses many to many rather than one to many.
- In 1970 IBM introduced IDMS(information data management system), a product based on the network data model.
Network data model
- Data Organisation in the network model is just like a graph rather than a tree, a child record can have any number of parent records
- This was the most widely used model before the relational database model was introduced
Features of the network data model
- It was introduced to overcome the drawbacks of the hierarchical model because the hierarchical model uses one to many relationship as a result only a few relationships can be established.
- Many to many relationships: But here in network model It uses many to many relationship where the child only is allowed to have more than one parent node as a result large number of relationships can be applied with different data tables and data access becomes easier and faster .
Example for or network data model
- Consider two tables “employee” table and “date of joining” table with the help of this network model more than one employee record can be linked to 2 more than and one record in the “date of joining” table
- For example, as shown in the figure both admin and HR uses the same data row present in the date of joining table i.e  as a result data duplicate is reduced .
Advantages of the network model
As more number of relationships or established between data tables it reduces data duplicity saves memory improve access time of data.