Types of Database Organization : The three common database structures are hierarchical, like a family tree arrangement; network, an adaptation of the hierarchical structure; and relational, the most flexible type of database organization. The three most common arrangements for database management systems are hierarchical, network, and relational. These three models have evolved gradually as users and computer specialists gained experience in using database management systems. They differ in terms of the cost of implementation, speed, degree of data redundancy and ease with which they can be updated.
The hierarchical and network database models were first developed and used principally on mainframe computers. The concepts behind the relational database model were pioneered. The relational database model, which takes advantage of large-capacity direct access storage devices, was developed for mainframe and minicomputer systems but is now also used on microcomputers. The relational database model is rapidly replacing the hierarchical and network models.
In a hierarchical database fields or records are arranged in related groups resembling a family tree, with “child” records subordinate to “parent” records. They may have more than one child but a child always has one parent.
Network Database Model
A network database is similar to a hierarchical DBMS but each child record can have more than one parent record. A child record may be reached through more than one parent.
Relational Database Model