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Summary
Databases penetrate virtually every branchof human activity, with relational databases (RDBMS) becoming the de-facto
standard. Some legacy database models — hierarchical and network databases —
are still in use, but relational database model (RDBM) holds the lion's share
of the market.
The RDBM resolves some of the inherent
problems of the legacy databases, and — with the advent of faster hardware and
support from the industry heavyweights — became the staple of every business
enterprise. The new object-oriented databases (OODMS) and object-oriented
relational database systems (OORDBMS) are evolving, though none has reached the
level of acceptance comparable with that of RDBMS.Most of the existing applications on the
market database use SQL as the standard language. There are three (four, by
some counts, if SQL86 is included) standards: SQL89, SQL92, and SQL99, with
virtually every RDBMS product being at least partially SQL92 compliant.
