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Network database concept was made by focusing the problem of hierarchical database model by representing data set using set theory which eliminates redundancy problems of the hierarchical model.The structure of this model is almost same like hierarchical without one that in this model a child can have more then one parent which allows many to many relationship.Another difference between the two models is
that the network model allows the structure to be navigated without having to start at the root
element.
Both the hierarchical and the network models have limitations. One limitation is that their
indexing scheme is tied to the sector scheme of the hard drive on which they reside, which
creates a mess if ever moved. Furthermore, it is difficult to query data from multiple tables.
Querying a database to retrieve data involves creating a program to navigate the database structure
to retrieve the requested data. These programs use procedural or proprietary languages that
require a great deal of knowledge and skill.
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