In your opinion what would make a company or organization migrate to a relational database architecture from a network or hierarchical architecture? What are some of the factors that should be considered when transferring data from one database architecture to another?
In a relational database, the logical design is independent of the physical design. Queries against a relational database management system are based on logical relationships and processing those queries does not require pre-defined access paths among the data (i.e., pointers). On the other hand, a hierarchical database is a series of flat-files linked in structured 'tree' relationships. This concept is fundamentally different from that used in relational model where data resides in a collection of tables without any hierarchy and that are physically independent of each other. Similarly, the network database model expands on the hierarchical model by providing multiple paths among segments (i.e., more than one parent/child relationship).
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 and with no restrictions on the number of relations, the database design can become overwhelmingly complex . The relational model provides the ...