MODERN DATA BASE
MANAGEMENT SYSTEMS
LECTURE NO 2
By Engineer Bilal Ahmad
Significance of Database Design
Database Design focuses on the Design of
the Database Structure used for End Users
Data.
 As a Designer you have to specify the
expected use of a Database.
 If you have a Well Designed Database it will
facilitate Data to be Managed Easily and it
will Generate valuable and accurate
information.
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Increase in the Productivity of an
Organization
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And you all are aware that how much important
is to have an accurate, precise and well managed
information for the Decision makers if the
organization wants to be in the Leading Role.
Just think about NADRA, they have an amazing
structure and management system that is used for
not only personal information but also
confidential stuff.
Effect of Poorly Designed Database
Angry Management.
 Miss handling of information.
 Wastage of time and Money.
 Un Happy and Angry Customers.
 Negative
feedbacks from Employees,
Administration and Management.
 End Product, Your Manager Says You are
no Longer in the Business and You loose
your job 
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Evolution of File System Data
Processing
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If you understand the complete complexity of
Design you are in a good command to tackle
unease situations.
If you understand the file system it will help to
avoid problems with the DBMS.
If you have a good command on File System you
will find it very useful to convert file system to
database system.
Evolution of File System Data
Processing continued
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File system is usually composed of collection of File
Folders, each tagged and kept in the cabinet that are
organized by expected use.
Remember Modern Database Management system
are on the basis of use and the frequency of usage.
Contents of Each file folders are logically related.
Lets say if I ask you to search Apples AND Bananas
on www.google.co.uk what information will you
achieve. And than if I ask you to have “OR”?
File Systems
Manual Systems:
Served as a data repository for small data collections.
Will be a miracle if you can manually feed data for a large
collection.
 Computerized File System:
Data Processing Specialist DP converted computer file
structure from manual system.
Wrote software that manage the data.
Design the Application programs.
Just remember when National ID Cards were not
Computerized because NADRA data base system was not
Computerized.
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File Systems Continued
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1.
2.
In the beginning computer file systems resembled the
manual system. All you were doing was using
computers for manual tackling and storing.
information. A simple example can be you can use
excel for manual storing and tracking information.
As a number of files increased. File system evolved
Each file to use its own application program to
store, retrieve and modify data.
Each file was owned by individual or department
that commissioned its creation.
A Simple File System
Problems with File System Data
Processing
File systems were an improvement over manual
systems.
 They have been used for more than 2 decades.
 Understanding the short comings of file systems
aids in the development of Modern Databases.
 The issues are;
Ad hoc queries are impossible.
Changing the existing structure is again a difficult
thing.

Data Redundancy
File system structure makes it difficult to
combine data from multiple sources.
 Organizational structure promotes storage of
same data in different locations.
 Data that has been stored in different
locations in unlikely to be updated
consistently.
 If same data is stored unnecessarily in
different places.

Data Redundancy Continued
Data inconsistency occurs when different and
conflicting versions of same data occur at
different places.
 When all changes in redundant data are not
made correctly that abnormalities take place. The
abnormalities occurs at the time of;
Updating
Inserting
Deleting

The Database System Environment
The Database System defines and regulates
the collection, storage and management of
the end user data.
 Five major parts/ components in a Database
system are; Hardware, software, people,
Procedures and Data.
 Hardware is the Physical Device.
 Software are of three types; OS, DBMS,
Application Programs and Software Utility

The Database System Environment
Recap
So Database Systems are created and
Managed at different levels of
complexity.
 Database
solutions must be costeffective as well as tactically and
strategically effective.

Chapter 2: Data Models
Now in this Chapter you will learn;
 About data modeling and why data models
are important.
 About the basic data modeling building
blocks.
 What are business rules and how they
influence database design.
 How data models can be classified by the
level of Abstraction.
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Data Modeling and Data Models
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Database Design focuses on how the Database
structure will be used to store and manage the end
user data.
The first step in designing a database should be
“understanding the problem and make a model”
What will happen if you don’t understand the
problem environment your system will collapse.
A problem domain is a clearly defined area within
the real world environment, with well defined
boundaries and scope, that is to be addressed
systematically.
What is a Data Model
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It is a relatively simple representation, usually
graphically of more complex real world structures.
A model is an abstraction of complex real world
problem.
It helps you to understand the complexities of an
environment.
Within a database environment a data model
represents data structures and their characteristics,
relations, constraints, transformation.
Data Model: A constructive way
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Data modeling is a very constructive way to
tackle a complex real time environment.
You start will basics and after getting into the
problem you come up with more and more idea
and your concepts get clears.
A stage will come that you will understand
each and every aspect.
Once your model is being created you make a
“Blue Print”, it is graphical in nature most of the
time.
What is “Blue Print”
It contains all the information to build a
database that will meet the end user
requirements. And as explained before that
it is normally in graphical form that explains
the abstraction level.
 Be prepared as an exercise will come
shortly, you will be asked to bake a cake
and total time will be 15 minutes.
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What will be the accurate Model
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Well the answer to that very statement is
complex.
Lets assume if you are asked to create a model
for a video store, you all will come up with
different ideas, the Blueprint will be different.
Now which one will be correct, it might be all of
you will be wrong, might be all of you will
produce the appropriate solution.
The answer will be however “the one that will
fulfill all the end user requirements”
The Importance of Data Models
It facilitates the interaction between the designer,
application programmer and the end users.
(there is an error in the above statement can you
think about it, it is not technically keep in mind)
 We can sum up the importance with a random
statement made by a client “I created the
business, I have worked with this business for 5
years but this is the first time I have really
understood how all pieces of information work
together”
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Importance of Data Models Continued
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It cannot be overstated.
Each and every member looks a Database in a
different fashion.
What information type will a Clerk Seek and
What information type will a Manager seek
Applications programmers have also another
way of viewing a data, they are concern about
the technicalities. What they do is they translate
the company policies.
Problems if you don’t have a Good
Blueprint
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It will not matter the point of view from different
personalities if you have a good blue print.
Can you think of some problems that will arise if
you don’t have a best blueprint.
You also have to keep in mind that a good
blueprint is an abstraction, it is not every thing.
Similar if you have to construct a house you need
to have a good blueprint.
Basic Building Blocks of Data Models
The basic building blocks are;
1. Entities
It describes a particular type of object in the
real world. It has to be distinguishable.
2. Attributes
It is a characteristic for entities, for example a
customers entity can be explained by address,
location, contact no etc.

DMBBB Continued
3. Relationships
A relationship describes an association among entities.
For example a relationship can be explained by some
statements.
An Agent can serve many customers and many
customers can be served by one Agent.
Three types of commonly relationships are used;
1.
One to One
2.
One to Many
3.
Many to Many
Relationship Explained
One to Many
A painter paints many painting but all paintings are
painted by one painter.
A customer may generate may invoices but all
invoices are generated by one customer.
 Many to Many
A student may learn many courses and many
courses are learnt by students.
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Relationship Continued
One to One
a retail store manager manages one store and
one store is being managed by one retail store
manager.
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All the above statements are business rules
and they are the exact information that has to
be used for Database Design.
DMBBB Continued
4. Constraint
A constraint is a restriction that is very important and
they are also called as set of rules.
“For example you cannot have a degree if your overall
CGPA is less than 2.5”
NB: In order to properly define entities, attributes,
relationships and constraints, you have to clearly
identify the business rules for the problem domains.
Remember you have to bake a Cake
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Ok, now you have to design a simple blueprint.
Should be explained in block diagram. What we
need is we need to Design a Database for a
Company named as Computer World.
Total no of employees are 2
Employees do have login information and than
they can access the system. The login will ask
there employee no and passwords.
Design Continued
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Total no of products that are offered to customers
are 10.
All products are displayed on shelves having
their product codes and price.
Tickets can be printed from the Database as the
record is already there.
If a sale person wants to search the stock he/ she
must have the facility to search the item using
product codes, as each and every product do
have different product codes.
Design Continued
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