Four types of DBMS:
Hierarchical DBMS: In a Hierarchical database, model data is organized in a tree-like structure. Data is Stored Hierarchically (top down or bottom up) format. Data is represented using a parent-child relationship. In Hierarchical DBMS parent may have many children, but children have only one parent. The idea behind hierarchical database models is useful for a certain type of data storage, but it is not extremely versatile. Its limitations mean that it is confined to some very specific uses. For example, where each individual person in a company may report to a given department, the department can be used as a parent record and the individual employees will represent secondary records, each of which links back to that one parent record in a hierarchical structure. Hierarchical databases were popular in early database design, in the era of mainframe computers.
Network DBMS: A
DBMS is said to be a Network DBMS if the
relationships among data in the database are of type many-to-many. The
relationship among many-to-many appears in the form of a network. Thus the
structure of a network database is extremely complicated because of these
many-to-many relationships in which one record can be used as a key of the
entire database. These have mainly been replaced by Relational database
management systems in today's modern computing. A network databases are mainly
used on a large digital computers. It more connections can be made between
different types of data, network databases are considered more efficiency.
Object-oriented DBMS: OODBMS represent significant
advance over other DBMS. While other DBMS are designed to handle structured
data, an OODBMS is designed to store data from variety of media sources, such
as photographs and text, and produce work, as output, in a multimedia format. It
takes more than storage of programming language objects. Object DBMS's increase
the semantics of the C++ and Java.
Relational DBMS: A DBMS is said to be a Relational
DBMS or RDBMS if the database relationships are treated in the form of a table.
The data can be related to other data in the same table or other tables which
has to be correctly managed by joining one or more tables. Data in this type of
model is stored is fixed predefined structures and are usually manipulated
using Structured Query Language (SQL). In relational databases, the
relationship between data files is relational. Hierarchical and network
databases require the user to pass a hierarchy in order to access needed data.
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