computer lecture

1. Database System
Today we will learn:
Some common uses of database systems
The characteristics of file-based systems
The problem with the file-based approach
The meaning of the term ‘Database’
The meaning of the term Database Management System’ (DBMS)
The typical functions of DBMS
The major components of the DBMS environment
The advantages and disadvantages of DBMSs

2. Database System
Data
Information
Summarized Data
Metadata

3. Database Systems
Purchase from the U-mart
Cash withdrawal from ATM (of The Bank of Punjab, Fowara Chowk, Gujrat)
Purchase using your credit card
Registration at NADRA office
Using the internet
University of Gujrat Information System (UOGIS)

4. Database Systems
A collection of programs that perform
services for the end-user.

5. Database Systems
Registration
Applications
Registration
Data
Files
Registration
Examination
Applications
Examination
Data
Files
Examination
Library
Applications
Library
Data
Files
Library

6. Database Systems
The Limitations of the file-based approach
Separation and isolation of data
Duplicate of data
Data dependence
Incompatible file formats

7. Database Systems
Fine
Books Issued
Father Name
Name
Reg_Number
Library
Grade
Semester
Class
Address
Name
Reg_Number
Examination
Class
Address
Phone
Father Name
Name
Reg_Number
Registration

8. Database Systems
-A software system that enables users to define, create, and
maintain the database and that provides controlled access to this
database.
A database management system (DBMS) is computer software that
manages databases.
Examples: Oracle, SQL Server, Informix, Sybase, Ingress

9. Database Systems
DBMS Database
containing
centralized
shared data
Application
#1
Application
#2
Application
#3

10. Database Systems
-Shared collection of logically related data (and a description of
this data), designed to meet the information needs of an
organization.

11. Database Systems
Shared collection – can be used simultaneously by many departments and
users.
Logically related - comprises the important objects and the relationships
between these objects.
Description of the data – the system catalog (meta-data) provides
description of data.

12. Database Systems
Database A collection of related files
^
File A collection of records about a particular set of people, objects, entities and so on
^
Record A collection of related fields associated with a single person, object, entity and so on
^
Field A collection of bytes representing a single attribute.
^
Byte A collection of bits representing a single character
^
Bit A binary digit

13. Database Systems
A database is a collection of integrated
files.
Integrated : Collection of files.
Note: A FILE is a collection of logical records in a tabular format.
A RECORD contains fields (or attributes ) about the entity.
A field is same as an ‘attribute’

14. Advantages of Database Approach
RegistrationExamination
Library
Applications
Library
Examination
Applications
Registration
Applications
Database
Management
System
University
Students
Database
- Data Sharing - Data Independence
- Controlled Redundancy - Better Data Integrity

15. Database Systems
Data Sharing
Data Independence
Controlled Redundancy
Better data Integrity
Data consistency
Better data security
Faster development of new applications
Economy of scale
Better concurrency
Better backup procedures

16. Database Systems
Higher costs (DBMS)
Conversion cost (manual to computerized )
More difficult recovery

17. Database System
Today we will learn:
•Database Users
•Typical Components of Database Environment
•Data Independence
•3-Level Architecture

18.  Application Programmers
 End Users
 Naïve
 Sophisticated
Instructor: Ikram. Database Systems. CS-212

19.  DatabaseAdministrator (DBA)
A person who has central control over data
and programs that access this data
Instructor: Ikram. Database Systems. CS-212

20. Functions of DBA
 Create Database
 Creating Users
 Granting Roles & Privileges
 Routine Maintenance
 Backups
 Monitoring disk space
 Monitoring jobs running
Instructor: Ikram. Database Systems. CS-212

21. Database
DBMS
“How” to get
Application Programs
“What” to get
End users
interact
Application
Programmers
Database
Administrators
Database
Designers
develop
maintain
design
Software
Users
Data

22.  Each user should be able to access the same data, but have a different
customized view of data. Each user should be able to change the way he or
she views the data, and this change should not affect other users.
 User should not have to deal directly with physical database storage
details.
 The internal structure of the database should be unaffected by the
changes to the physical aspects of storage, such as change over to a new
storage devices.

23. External Level
Conceptual / Logical Level
Internal Level
Physical Data
Organization
View 1 View 2 View n
Conceptual
Schema
Internal
Schema
Database
User 1 User 2 User n
Ext/Con Mapping
Con/Int Mapping
3-Level Architecture

24.  This Level Describes-The Part of Database that is
relevant to each user e.g. Registration,Accounts etc
 Calculated Data:That is not actually stored in the
database but is created when needed e.g. age
 DBMS uses external views to create users interface for
different users which is both the facility and barrier.
 External Schema are evolves as user needs are
modified over time

25. First Name: Rana
Last Name: Aslam
Date of Birth:
12 Sep, 1970
Name: R. Aslam
Age: 24y,10d
Dept: Sales
Saleem
Saleema
Corresponds to different views of Data
External Level

26.  Entire information structure of the database.
 Also called “The Community view of data”
 All entities, attributes and their relationships are represented.
 Representing data and constraints on data
 Contains information about the security and integrity
information
 Relatively constant: designed with the present as well as future
needs of an organization.

27. Name DoB DepId
Rana Aslam 12/09/70 D001
Marya Wasti 29/02/80 D005
First Name: Rana
Last Name: Aslam
Date of Birth:
12 Sep, 1970
Name: R. Aslam
Age: 24y,10d
Dept: Sales
Saleem
Saleema
Conceptual / Logical View
Describes all entities their attributes their relationships with constraints

28.  Although these are at same level but
 PhysicalView
▪ Actual Data (on the disk) binary format.
▪ Use OS to store the Data
 InternalView
▪ Internal Record: a single stored record
▪ Does not just contain what we see at the conceptual
level

29. Name DoB Deps DepId
Rana Aslam 12/09/70 5 D001
Marya Wasti 29/02/80 0 D005
First Name: Rana
Last Name: Aslam
Date of Birth:
12 Sep, 1970
Name: R. Aslam
Age: 24y,10d
Dept: Sales
Saleem
Saleema
01110011010011100101001010100101010010101…..
BH RH Rana Aslam 120970 5 D001 RH Marya Wasti…
Contains stored Data (Record)
Internal View

30.  External / Conceptual mapping
 (correspondence between external level and
conceptual level)
 Conceptual / Internal
 (correspondence between and conceptual level
and internal level)

31. Specifies mapping between objects in the
external view to those in the logical model
External to logical model

32. Specifies mapping between objects in the
logical model to those in the physical model-
data independence
 Logical to Physical

34.  Very Important Feature
 Data independence is major most outcome of 3-L Arch
 The immunity of applications to change in storage
structure and access strategy

35. Changes in lower level do not affect the upper
levels
 Mind the direction please

36.  Logical Data Independence
 Physical Data Independence

37.  Changes in conceptual model do not affect the
external views
 Immunity of external level from changes at
conceptual level

38.  Adding a new file etc.
 Adding a new field in a file
 Changing type/size
 Deleting an attribute

39.  Changes in the internal model do not affect the
conceptual model
 Immunity of Conceptual level from changes at
Internal level

40.  Entity (an object)
 Attribute (characteristics of object)
 Constraints (limit, check, control)