2. What is DBMS ?
A database management system (DBMS) is a computersoftware
application that interacts with the user, other applications, and the database
itself to capture and analyse data. A general-purpose DBMS is designed to
allow the definition, creation, querying, update, and administration of
databases. Sometimesa DBMS is looselyreferred to as a 'database'.
Types of databases
The differentdatabase types are:
1. Centralised database
2. Operational database
3. End-user database
4. Personal database
5. Distributed database
6. Commercial database
1. Centralised database
Users from differentlocations can access this database from a remote
location at the central database, that store entire information and
application programs at a central computing facility for processing.The
application programs pick up the appropriate data from the database based
on the transactions sent by the communications controller for processing
the transaction.
Data validation and verification is carried out by the application programs at
the central computercentre, and a registration number is allotted by the
3. application programs located at the central facility. The local area office
keeps on recording it and hardly does any processing.
2. Operational database
This is more of a basic form of data that contain information relating to the
operations of an enterprise. Generally, such databases are organised on
functional lines such as marketing, production,employees,etc.
3. End user database
End user is the user of a software, application or a product. This is a
shared database which is shared by users and is meant for use by the end
users, just like managers at differentlevels. They may not be concerned
about the individual transactions as found in operational databases. This
database is more about the summary of the information.
4. Commercial database
This is a database that contains information which external users may
require. However, they will not be able to afford maintaining such huge
database by themselves.It’s a paid service to the user as the databases
are subject specific.The access to commercialdatabase can be given
through commerciallinks.
Some of the database service providers also offerdatabases on CD-ROMs
and the updated versions of the databases are made available periodically.
The databases on CD-ROMs have the advantage of reduced costof
communication.
4. 5. Personal database
The personal databases are maintained, generally, on personalcomputers.
They contain information that is meant for use only among a limited number
of users, generally working in the same department.
6. Distributed database
These databases have contributions from the commondatabases as well
as the data captured from the local operations.The data remains
distributed at various sites in the organisation. As the sites are linked to
each other with the help of communication links, the entire collectionof
data at all the sites constitutes the logical database of the organisation.
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Example of data base
Access
Accessis a personaldatabase system from Microsoft. It is a visually
oriented softwareproduct, making it easy for non-programmers to develop
useful databases. While the Access database structure can scale up to
5. serve corporate needs,the most commonuse for this database is for small
individual databases or limited-use multiuser programs.It integrates the
Visual Basic for Applications language, making it a completedevelopment
environment.
Visual FoxPro
FoxPro is a relational database system,also produced byMicrosoft,that is
tightly coupled to its programming language. FoxPro is less friendly as an
end-user database, requiring more technical expertise then Access.This
database system is known for its fast processing engine and the ability to
handle numerous simultaneous transactions.
MySQL Database
MySQL is a server-based database that enables multiple users to access
multiple databases.The software runs on multiple platforms,including most
varieties of UNIX and Windows.It offers limited front-end usability, and is
designed as a back-end database server. MySQL separates from other
database products and their costs;the non-enterprise version is distributed
for free.
6. SQL Server
SQL Server is an enterprise-levelscalable database server. This product
differs from the personal database in that it doesn'tprovide the front-
end tools that an individual database product would provide.The database
engine focuses on quickly responding to client requests in the form of SQL
queries. These queries can be generated directly in SQL Server, or through
a separate user interface developedin a multitude of programming
languages. SQL Server is designed to handle databases with millions of
records.
Oracle
The Oracle database is another enterprise-levelscalable database. The
SQL-based database supports distributed corporate databases,enabling
the user to access data locally or from remote databases in a transparent
transaction. Distributed databases help to overcome the physical limitations
of a physical computing environment. The maximum database size for an
Oracle database is 8 million terabytes, requiring physical storage beyond
the capacity of mostsingle installations.
What is traditional file system ?
The traditional filing system (TFS) is a method of storing and arranging
computerfiles and the information in the file (data). Basically it organizes
these files into a database for the storage, organization, manipulation, and
retrieval by the computer's operating system.
(DBMS) consists of software that operates databases, providing storage,
access,security, backup and other facilities. This system can be
categorized according to the database modeland the type of computerthat
they support such as a server cluster or a mobile phone, the query
7. language(s) that access the database, such as SQL or XQuery,
performance trade-offs,such as maximum scale or maximum speed or
others. Some DBMS cover more than one entry in these categories,e.g.,
supporting multiple query languages.
Advantages
Control of data redundancy
Although the database approach does not remove redundancy completely,
it controls the amount of redundancy in the database.
Data consistency
By removing or controlling redundancy, the database approach reduces the
risk of inconsistencies occurring.It ensures all copies of the idea are kept
consistent.
More information from the same amount of
data
With the amalgamation of the operated data, it is possible to derive
additional information for the same data.
Sharing of data
Database belongs to the entire organization and can be shared by all
authorized users.
Improved data integrity
Database integrity provides the validity and consistencyof stored data.
Integrity is usually expressed in terms of constraints, which are consistency
rules that the database is not permitted to violate.
Improved security
8. Provides protectionof data from unauthorized users. It will require user
names and passwords to identify user type and their access right in the
operation including retrieval, insertion, updating and deletion.
Enforcement of standards
The integration of the database enforces the necessarystandards including
data formats,naming conventions, documentationstandards, update
procedures and access rules.
Economy of scale
Cost savings can be obtained by combining all organization's operational
data into one database with applications to work on one source of data.
Balance of conflicting requirements
By having a structural designin the database, the conflicts between users
or departments can be resolved.Decisions will be based on the base use
of resources forthe organization as a whole rather than for an individual
person.
Improved data accessibility and
responsiveness
By having integration in the database approach, data accessing can cross
departmental boundaries. This feature provides more functionality and
better services to the users.
Increased productivity
The database approach provides all the low-level file-handling routines.
The provision of these functions allow the programmerto concentrate more
on the specific functionalityrequired by the users. The fourth-generation
environment provided by the database can simplify the database
application development.
Improved maintenance
9. Provides data independence.As a change of data structure in the database
will affectthe application program, it simplifies database application
maintenance.
Increased concurrency
Database can manage concurrent data access effectively.It ensures no
interference between users that would not result any loss of information or
loss of integrity.
Improved backing and recovery services
Modern database management system provides facilities to
minimize the amount of processing that can be lost following a
failure by using the transaction approach.
Database Administrator (DBA)
DBA is also an abbreviation for doing business as - a term sometimesused
in business and legal writing. dBA is an abbreviation for A-weighted
decibels.
A database administrator (DBA) directs or performs all activities related to
maintaining a successful database environment. Responsibilities include
designing, implementing, and maintaining the database system;
establishing policies and procedurespertaining to the
management, security, maintenance, and use of the database
management system; and training employees in database management
and use. A DBA is expected to stay abreast of emerging technologies and
new design approaches.
10. Database Management System
(DBMS)
A database management system (DBMS) is system software for creating
and managing databases. The DBMS provides users and programmers
with a systematic way to create, retrieve, update and manage data.
A DBMS makes it possible for end users to create, read, update and
delete data in a database. The DBMS essentially serves as an interface
between the database and end users or application programs, ensuring
that data is consistently organized and remains easily accessible
Relational Database Management
system (RDBMS)
A relational database management system (RDBMS) is a program that
lets you create, update, and administer a relational database. Most
commercial
RDBMS's use the Structured Query Language (SQL) to access the
database, although SQL was invented after the development of the
relational model and is not necessary for its use.
The leading RDBMS products are Oracle, IBM's DB2 and
Microsoft's SQL Server. Despite repeated challenges by competing
technologies, as well as the claim by some experts that no current
RDBMS has fully implemented relational principles, the majority of new
11. corporate databases are still being created and managed with an
RDBMS
Data Base Model
A database model shows the logical structure of a database, including
the relationships and constraints that determine how data can be
stored and accessed. Individual database models are designed based
on the rules and concepts of whichever broader data model the
designers adopt.
Types of database models
Some of the most common ones include:
Hierarchical database model
Relational model
Network model
Object-oriented database model
Entity-relationship model
Document model
Entity-attribute-value model