General-purpose and special purpose DBMSs

A DBMS has evolved into a complex software
system and its development typically requires
thousands of person-years of development
effort. [4] Some general-purpose DBMSs such
as Adabas, Oracle and DB2 have been
undergoing upgrades since the 1970s. General-
purpose DBMSs aim to meet the needs of as
many applications as possible, which adds to
the complexity. However, the fact that their
development cost can be spread over a large
number of users means that they are often the
most cost-effective approach. However, a
general-purpose DBMS is not always the
optimal solution: in some cases a general-
purpose DBMS may introduce unnecessary
overhead. Therefore, there are many examples
of systems that use special-purpose databases.
A common example is an email system: email
systems are designed to optimize the handling
of email messages, and do not need significant
portions of a general-purpose DBMS
functionality.
Many databases have application software that
accesses the database on behalf of end-users,
without exposing the DBMS interface directly.
Application programmers may use a wire
protocol directly, or more likely through an
application programming interface . Database
designers and database administrators interact
with the DBMS through dedicated interfaces to
build and maintain the applications' databases,
and thus need some more knowledge and
understanding about how DBMSs operate and
the DBMSs' external interfaces and tuning
parameters.

Applications

Databases are used to support internal
operations of organizations and to underpin
online interactions with customers and
suppliers (see Enterprise software ).
Databases are used to hold administrative
information and more specialized data, such as
engineering data or economic models.
Examples of database applications include
computerized library systems, flight reservation
systems and computerized parts inventory
systems .

Terminology and overview

Formally, "database" refers to the data
themselves and supporting data structures.
Databases are created to operate large
quantities of information by inputting, storing,
retrieving and managing that information.
Databases are set up so that one set of
software programs provides all users with
access to all the data.
A "database management system" (DBMS) is a
suite of computer software providing the
interface between users and a database or
databases. Because they are so closely related,
the term "database" when used casually often
refers to both a DBMS and the data it
manipulates.
Outside the world of professional information
technology, the term database is sometimes
used casually to refer to any collection of data
(perhaps a spreadsheet , maybe even a card
index). This article is concerned only with
databases where the size and usage
requirements necessitate use of a database
management system. [1]
The interactions catered for by most existing
DBMSs fall into four main groups:
Data definition – Defining new data
structures for a database, removing data
structures from the database, modifying the
structure of existing data.
Update – Inserting, modifying, and deleting
data.
Retrieval – Obtaining information either for
end-user queries and reports or for processing
by applications.
Administration – Registering and monitoring
users, enforcing data security, monitoring
performance, maintaining data integrity, dealing
with concurrency control, and recovering
information if the system fails.
A DBMS is responsible for maintaining the
integrity and security of stored data, and for
recovering information if the system fails.
Both a database and its DBMS conform to the
principles of a particular database model . [2]
"Database system" refers collectively to the
database model, database management system,
and database. [3]
Physically, database servers are dedicated
computers that hold the actual databases and
run only the DBMS and related software.
Database servers are usually multiprocessor
computers, with generous memory and RAID
disk arrays used for stable storage. RAID is
used for recovery of data if any of the disks fail.
Hardware database accelerators, connected to
one or more servers via a high-speed channel,
are also used in large volume transaction
processing environments. DBMSs are found at
the heart of most database applications . DBMSs
may be built around a custom multitasking
kernel with built-in networking support, but
modern DBMSs typically rely on a standard
operating system to provide these
functions. [ citation needed ] Since DBMSs
comprise a significant economical market ,
computer and storage vendors often take into
account DBMS requirements in their own
development plans. [ citation needed ]
Databases and DBMSs can be categorized
according to the database model(s) that they
support (such as relational or XML), the type(s)
of computer they run on (from a server cluster
to a mobile phone), the query language (s) used
to access the database (such as SQL or
XQuery ), and their internal engineering, which
affects performance, scalability , resilience, and
security.

Types of DBMS !

There are four main types of database
management systems (DBMS) and these are
based upon their management of database
structures. In other words, the types of DBMS
are entirely dependent upon how the database
is structured by that particular DBMS.

Hierarchical DBMS:-
A DBMS is said to be hierarchical if the
relationships among data in the database are
established in such a way that one data item is
present as the subordinate of another one or a
sub unit. Here subordinate means that items
have "parent-child" relationships among them.
Direct relationships exist between any two
records that are stored consecutively. The data
structure "tree" is followed by the DBMS to
structure the database. No backward movement
is possible/allowed in the hierarchical database.
The hierarchical data model was developed by
IBM in 1968 and introduced in information
management systems. This model is like a
structure of a tree with the records forming the
nodes and fields forming the branches of the
tree. In the hierarchical model, records are
linked in the form of an organization chart. A
tree structure may establish one-to-many
relationship.....

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 relationships 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. A network database is structured in
the form of a graph that is also a data
structure. Though the structure of such a DBMS
is highly complicated however it has two basic
elements i.e. records and sets to designate
many-to-many relationships. Mainly high-level
languages such as Pascal , C++ , COBOL and
FORTRAN etc. were used to implement the
records and set structures.

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. There are three keys on
relational DBMS: relation, domain and
attributes. A network means it contains a
fundamental constructs sets or records.sets
contains one to many relationship,records
contains fields statical table that is composed of
rows and columns is used to organize the
database and its structure and is actually a two
dimension array in the computer memory. A
number of RDBMSs are available, some popular
examples are Oracle, Sybase , Ingress, Informix ,
Microsoft SQL Server, and Microsoft Access .

Object-oriented DBMS:-
Able to handle many new data types, including
graphics, photographs, audio, and video, object-
oriented databases represent a significant
advance over their other database cousins.
Hierarchical and network databases are all
designed to handle structured data; that is, data
that fits nicely into fields, rows, and columns.
They are useful for handling small snippets of
information such as names, addresses, zip
codes, product numbers, and any kind of
statistic or number you can think of. On the
other hand, an object-oriented database can be
used to store data from a variety of media
sources, such as photographs and text, and
produce work, as output, in a multimedia
format. [1]
Object-oriented databases use small,
reusable chunks of software called objects. The
objects themselves are stored in the object-
oriented database. Each object consists of two
elements: 1) a piece of data (e.g., sound, video,
text, or graphics), and 2) the instructions, or
software programs called methods, for what to
do with the data. Part two of this definition
requires a little more explanation. The
instructions contained within the object are
used to do something with the data in the
object. For example, test scores would be
within the object as would the instructions for
calculating average test score.
Object-oriented databases have two
disadvantages. First, they are more costly to
develop. Second, most organizations are
reluctant to abandon or convert from those
databases that they have already invested
money in developing and implementing.
However, the benefits to object-oriented
databases are compelling. The ability to mix and
match reusable objects provides incredible
multimedia capability. Healthcare organizations,
for example, can store, track, and recall CAT
scans, X-rays, electrocardiograms and many
other forms of crucial data.

What is mean by DBMS?

DBMS is software that allows access to data contained in dataDatabase
A database is an organized collection of data .
The data are typically organized to model
relevant aspects of reality in a way that
supports processes requiring this information.
For example, modelling the availability of rooms
in hotels in a way that supports finding a hotel
with vacancies.
Database management systems (DBMS s) are
specially designed software applications that
interact with the user, other applications, and
the database itself to capture and analyze data.
A general-purpose DBMS is a software system
designed to allow the definition, creation,
querying, update, and administration of
databases. Well-known DBMSs include MySQL ,
MariaDB , PostgreSQL, SQLite, Microsoft SQL
Server, Oracle , SAP HANA , dBASE , FoxPro , IBM
DB2 , LibreOffice Base , FileMaker Pro, Microsoft
Access and InterSystems Caché . A database is
not generally portable across different DBMSs,
but different DBMSs can interoperate by using
standards such as SQL and ODBC or JDBC to
allow a single application to work with more
than one database. There are different types of
database, some of them are as follows:
Operational Database Specific Database External
Database Hypermedia Databasease.