Lect_2_dbms_its_rnvironment_and_components

Lect 2 on dbms

1. Lecture 2
Database System (INFT-4006)

2. Database
“Asharedcollectionof
logicallyrelateddata
anditsdescription,
designedtomeetthe
informationneedsofan
organization”

3. Database
•Database is collection of information
managed by Database management
system
•It is a single large collection (repository)
of data shared among users
•All data items are integrated with
minimum duplication
•Database is shared corporate resource
•Database not only contains operational
databutalsodescriptionofdata

4. Database
•The self describing nature of database
provides “program-data independence”
•The definition of data is separated from the
application program
•The structure of data is not affected by the
program and vice versa
•If new data structures are added or existing
data structures are modified, they do not
affect the application program (if program
does not directly depend on what has been
modified)
•Forexampleifweremoveafieldthatis

5. Branch Staff
PropertyForRent Client
LeasePrivateOwner
Ha
s
Oversees
ViewsOffers
Own
s
Leased
By
Hold
s

6. What is meant by
logically related?

7. •When we design a database we identity entities, attributes and
relationships between these entities
AnAttributeisapropertythatdescribesomeaspectofentity
that we wish to record
A relationship is an association between entitles
AnEntitysdistinctobjectthat
istoberepresentedin
database

8. •When we design a database we identity entities, attributes and
relationships between these entities
AnAttributeisaproperty
thatdescribesomeaspectof
entity that we wish to record
A relationship is an association between entitles
An Entity s distinct object that is to be represented in database

9. •When we design a database we identity entities, attributes and
relationships between these entities
AnAttributeisapropertythatdescribesomeaspectofentity
that we wish to record
A relationship is an
association between entitles
An Entity s distinct object that is to be represented in database

10. Database
Management
System
•A software system that enables users to
define, create, maintain, and control
access to the database is called DBMS
•DBMS provides user the facility:
–To define database through DDL (Data
definition Language)
–To allow users to insert, update, delete and
retrieve data from the database through DML
(Data manipulation language)
–These facilities are provided through query
languages
–Most common query language is “SQL”

11. (Database)
Application
Programs
•A computer program that interacts with
the database by issuing an appropriate
request to DBMS is call Application
Program
•Users interact with database through
Application program
•Application programs are written in high
level programming languages or higher
level programming languages (fourth
generation languages e.g. SQL)

12. Admission
Departmen
t
Exam
Departmen
t
Library
Departmen
t
Registratio
n File
Registratio
n File
Registratio
n File

13. Data Entry and
Reports
Data Entry and
Reports
DBMS
Registration
Database
Exa
m
Fe
e
Fee
application
program
Exam
application
program

14. Views
•DBMS provide a View Mechanism to allow
each user to have his or her own view of
the database
•Views have several benefits like:
–View can be set up to exclude data that some
users should not see
–View provides mechanism to customize
–View provides an unchanging picture of the
structure of the database even if the underlying
database structure is changes

15. Components
of Database
Compone
nts of
DBMS
Hardwa
re
Softwar
e
Data
Procedu
re
People

16. Hardware
•Thehardwarereferstothephysicalparts
ofthecomputerandItalsoincludes
variousstoragedeviceslikeharddisksand
input-outputdeviceslikemonitors,
printers etc.
•Hardwareisthemostvisiblepartofany
informationsystem:theequipmentsuch
ascomputers,scannersandprintersthat
areusedtocapturedata,transformitand
present it to the user as output.
•Thehardwareistheactualcomputer
systemusedforkeepingandaccessingthe
database.
•Servershavelargedatastoragecapacities
enablinguserstosharefilesand
applicationsoftwarealthoughprocessing

17. Hardware
•Workstations, which provide high-level
performance for individual users in
computationally intensive fields such as
engineering.
•Databases run on a range of machines
from microcomputers to mainframes. This
also provides the interface between
computers and real-world systems.
•When we run Oracle or MySQL on our
personal computer, then our computer’s
hard disk, our keyboard with which we
type in all the commands, our computers
RAM, and ROM all become a part of the
DBMS hardware.

18. Software
•The main component of a Database
management system is the software.
•Software is a collection or set of programs
or instructions that tell a computer what to
do. The software comprises the entire set
of programs, procedures, and routines
associated with the operation of a
computer system. A set of instructions that
directs a computer’s hardware to perform
a task is called a program, or software
program.
•It also includes the database software,
operating system, network software used
to share the data with other users, and the
applications used to access the data.
•

19. Software
• This software component is capable of
understanding the Database Access
Language and converting it into actual
database commands to execute or run
them on the database.
•This is the main component, as this is the
program which controls everything. The
DBMS software is more like a wrapper
around the physical database, which
provides us with an easy-to-use interface
to store, access and update data.
•Some DBMS software examples include
MySQL, PostgreSQL, Microsoft Access, SQL
Server, FileMaker, Oracle, RDBMS, dBASE,
Clipper, and FoxPro

20. Data
• The word data covers the collection of
facts stored in the database. Because data
are the raw material from which
information is generated
• Data stored in the database includes
structure data, non-structural data, and
logical data.
•Structured data is highly specific and is
stored in a predefined format, whereas
unstructured data is a conglomeration of
many varied types of data that are stored
in their native formats. This means that
structured data takes advantage of schema-
on-write and unstructured data employs
schema-on-read.
•Using a DBMS the database is first
constructed, created or defined. After that,
thedesireddataisstoredaccessedand

21. Data
•The primary reason behind the
introduction of the database management
system is to store and maintain the data
within the database
•It is the most important component of the
database management system. The typical
database contains both the metadata(data
about data) and the actual(operational)
data.
•For example – when I store my name in a
database, the DBMS will store when the
name was stored in database, what is the
size of the name, is it stored as related data
to some other data?, or is it independent?,
all this information is Metadata.

22. Procedure
•Procedures refer to general instructions to
use a database management system. This
includes procedures to set up and install a
DBMS, To login and logout of DBMS
software, manage databases, take backups,
generate reports etc.
•Procedures can be used for data validation,
access control, or to reduce network traffic
between clients and the DBMS servers.
Extensive and complex business logic can
be embedded into the subroutine, thereby
offering better performance.
•

23. Procedure
•The basic purpose of the procedures is to
help guide users in the operation and
management of database systems.
•Database Procedures are similar to
Database Functions. The major difference
is the way in which they are invoked –
Database Functions can be used in the
same way as for any other expression
within SQL statements, whereas Database
Procedures must be invoked using the
CALL or EXEC statement, depending on the
DBMS.
•In Enterprise Architect, Database
Procedures can be modelled in one of two
ways:
–Asindividualobjects(thedefaultmethod)

24. People
•People perform different roles in database
environment
–Data Administrator
–Database Administrator
–Database Designer
–Application Developer
–End Users

25. Any Question?