Early Database models: File Management System, Hierarchical, Network Database

File Management System: Before database management systems and database models, there used to be file management systems. A file management system keeps record of the name and location of files. The contents of the file remained unknown to the file management system. Contents of file were known to the application programs which run in the computer system. This type of arrangement was used generally used for Payroll management. The disadvantage of file management system is that if data is modified for files then all the associated application programs have to be changed.

Hierarchical Database: Before DBMS, another approach which came in to effect was the use of hierarchical database. In this system, components are broken down to tree like hierarchies and then records are navigated in hierarchical database. It provided a simple parent child relationship among the records. Processing of records was swift in this database model. IBM created (IMS) Information Management System by the use of this concept. The disadvantage of this model is that it doesn’t work for complex systems.

Network Database: This database model was used for order processing. It uses the same basic concept of a hierarchical database. However, it extends it by allowing multiple parent and child relationships. In this model, keys were used for navigation between records. It provided a flexible and standard approach to navigate between records. Again, processing of records was swift in this database model. Disadvantage of this approach was that it was a difficult task to change the structure of the database.

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