DBMS

1. NETAJI SUBHASH ENGINEERING COLLEGE
TOPIC:DBMS INTRODUCTION,FILE SYSTEM VS DBMS,THREE SCHEMA ARCHITECTURE
NAME : SYED TARIQUE ABEDIN
ROLL : 158
U.ROLL :10900120162
SEC : C
STREAM: CSE(6TH SEM)

2. DBMS INTRODUCTION
*What is DBMS?
Database Management System (DBMS) is a software application that is
used to create, access, maintain, and manage databases. We can install it
like any other application and use SQL for all the operations that we intend
to perform on databases. DBMS accepts the incoming data either from an
application or from a user who is manually entering it.
• It does not matter if it is a large or small DBMS, with its help, we can store
and retrieve data and make changes whenever we want to.
• Some commands are predefined in DBMS, and these commands can be
used to manipulate the database. These commands are also the interface
between the database and end-users to establish communication.

3. Database Management System Examples
• Oracle – Oracle is a Relational Database ManagementSystem. It can be stored on-site or in the
cloud. It uses enterprise-scale technology to offer a wide range of features to the users.
• MySQL– Used by platforms like Youtube , Twitter, and Facebook, MySQL is a Relational
DatabaseManagement System. It is often integrated with open-source Content Management
Systems (CMS).
• SQL Server – SQL Server is a Relational DatabaseManagement System developed by Microsoft.
It was based on SQL, a query language that helps users in data query and database
management.
TYPES OF DBMS
• HIERARCHICAL DATABASES
• NETWORK DATABASES
• RELATIONAL DATABASES (RDBMS)
• OBJECT-ORIENTED DATABASES

4. DBMS ADVANTAGES AND DISADVANTAGES
ADVANTAGES OF DBMS
• Variousformatsof datacan be stored,anddata can be retrievedbyarange of
methodsinthe StructuredQueryLanguage.
• Asmost databasesare usuallycentralizedinnature,theycanbe accessed
quicklyandmanagedeasily.
• We can setup authorizeduserswhocanview,share,andaccessdata.This
ensuressecurityfordata.
• DBMS facilitatesthe smoothincorporationof programminglanguages,suchas
C++, Python,andPHP,to allowuserstoestablishaconnectionwithaweb
applicationorthird-partyapplications.
• To preventdatafrombeinginaccessiblewhenthere isanoverload,arecovery
systemwithautomatedbackupsisprovidedbyalmosteveryDBMSsoftware.
• Withminimumdataduplicityandredundancy,DBMSprovidesdataprotection
and integrity.
DISADVANTAGES OF DBMS
• In some cases,DBMSsare highlycomplicatedsystemstosetupandmaintain.
• The cost of DBMS hardware and applicationsiscomparativelyhigh,exhausting
an organization’sbudget.
• In certainorganizations,all informationisintegratedintoacommondatabase,
whichmayget destroyeddue toelectrical issuesoritmaygetcorruptedin
storage media.Havingbackupsispreferredinsuchsituationsbutthatincreases
the cost.
• CertainDBMS systemscannotruncomplex queriesastheyslowdownthe other
processesthatare running.

5. FILE SYSTEM VS DBMS
FILE SYSTEM DBMS
Used to manage and organise the files stored in
the hard disk of the computer
A software to store and retrieve the user’s
data
Redundant data is present No presence of redundant data
Query processing is not so efficient Query processing is efficient
Data consistencyis low Due to the process of normalisation, the data
consistencyis high
Less complex, does not support complicated
transactions
More complexity in managing the data, easier
to implement complicated transactions
Less security Supports more security mechanisms
Less expensive in comparison to DBMS Higher cost than the File system
Does not support crash recovery Crash recovery mechanism is highly supported

6. THREE SCHEMA ARCHITECTURE
• The three schema architecture is
also called ANSI/SPARC
architecture or three-level
architecture.
• This framework is used to
describe the structure of a
specific database system.
• The three schema architecture is
also used to separate the user
applications and physical
database.
• The three schema architecture
contains three-levels. It breaks
the database down into three
different categories.

7. OBJECTIVES OF THREE SCHEMA
ARCHITECTURE
• Differentusers need differentviews of the same data.
• The approach in which a particular user needs to see
the data may changeover time.
• The users of the database should not worry about the
physical implementation and internal workings of the
database such as data compression and encryption
techniques, hashing, optimization of the internal
structures etc.
• 1. Internal Level: The internal level has an internal
schema which describes the physical storage
structureof the database.
• 2. Conceptual Level: The conceptual schema
describes the design of a database at the conceptual
level. Conceptual level is also known as logical level.
• 3. External Level: At the external level, a database
contains several schemas that sometimes called as
subschema. The subschema is used to describe the
differentview of the database.