Download Elements of Database System

Normalized bubble chart for Data
in the Instructor’s View
Instructor
Standard fee
Course +
Date
Participant
Organization
Text book
Title
Grade
Normalized bubble chart
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View Integration
◦ Techniques are available for integrating bubble
charts representing individual user views into
a composite logical schema of all data items
contained in the various views.
◦ Detailed description of view integration using
bubble charts was given by Martin 1983.
◦ The integrated view of the participant’s
bubble chart and the instructor’s bubble chart
is shown on next slide
Bubble Chart integrating the instructor’s view and
the course promoter’s view
Instructor
High degree
university
year
Course +
Date
Text
book
Overall
rating
fee
Participant
Grade
Title
Organization
City
zip
Prospect
Title
street
Bubble Chart integrating the instructor’s view
and the course promoter’s view
•If these were the only two views in the module,
then this would be one form of logical schema
for the database, because it contains all data
elements and relationships necessary to support
the user view in the module. Furthermore, all
necessary redundancies have been eliminated.
•This is the minimal set of data elements and
relationships necessary to support the individual
user views.
Elements of Database Systems
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Physical design:
◦ The last step of the database design process is
physical design.
◦ Physical design involves
 converting the software schema into a form implementable
with the organization’s particular hardware, operating system
and database management system
 Designing navigation path
 Deciding which records to place in nearby portions of the
storage devices
 Determining the size of physical records on storage devices
but buffer areas in main memory to hold records
 Implementing integrity and security requirements.
Other database Techniques &
Procedures
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It includes procedures for
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Analysing
Implementing
And operating system
Designing and documenting program
Training users
Databases
Databases are
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Integrated
Shared collections of files
Stored on these devices of the organizations
computer system
The way the data is organized and stored on
these devices is referred to as its physical
organization
In terms of logical organization. There are
many different ways that databases can be
organized
Software
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There are three different kinds of
software involved in most database
systems
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Database management packages
Operating system
Applications program
Most DBM packages use the basic access
methods of the host operating system to
perform the necessary input-output
operations on the data files themselves
Database Management Systems
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The minimum components of a package
that could truly be called a DBMS are
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Data dictionary
Data definition language
Query languages
Data manipulation language
Report generator language
Features to support data integrity
Security, privacy, recovery
Database Management System
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Data Dictionary
◦ Is used to maintain standard definitions of all
data items within the scope of the DB system
◦ The purpose of DD is to enforce standard
definitions of the data resources of the
organization.
◦ Definition includes a precise description of
the meaning of a data item name and a
precise description of how values of each data
item are stored in the computer system.
Database Management System
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Data Dictionary
◦ Functions of DD
 Maintaining standard user definitions of the precise
meaning of data items and data types
 Maintaining cross reference list of data items used
 Providing standard definitions of data items to
applications programs
◦ Examples
 Name structure
 Last name
 First name
 Address
 Dept code
datatype is text and size is 15 characters
dtatype is text and size is 10 characters
copy from
data type is unsigned numeric size is 3 dig
Database Management Systems
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Data Definition Languages
◦ Is used to translate the logical schema into a
software schema for the DBM package in use
◦ Defined by CODASYL committee
◦ Two languages were defined
 DDL
 SQL
Database Management systems
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Query Languages
◦ SQL
◦ Fourth Generation languages
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Binary
Assembly
COBOL
FORTRAN
PASCAL
People: The Most important
Element
The primary concerns of Users
 User views of Data & information
 The Role of Top Management
 The Systems Staff and its Role
◦ The Manager of Information Resource
◦ Information Analyst
◦ Database Analyst
 The User’s View
◦ Database application programmer
◦ Database Administrator
◦ A comment on sharing Role
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Thanks very much!!
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