INTRODUCTION TO DATABASE ITDA1001

ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 1
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INTRODUCTION TO DATABASE
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 2
Topics
• Data
• Managing the Data
• Data and Database
• Problems with the Traditional File Environment
• Flat File System
• Traditional File Environment: Other Problems
• The Hierarchy of Data
• What is a DBMS?
• Database Management System
• The DBMS as the Interface
• Advantages of a DBMS
• Other Advantages of a DBMS
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 3
Topics (Cont…)
• Results of using Database Approach
• When not to use a DBMS
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 4
Data
• Data is a collection of facts, such as numbers, words,
measurements, observations or even just descriptions of
things.
• Data can be qualitative or quantitative.
– Qualitative data is descriptive information.
• Example:
– He is brown and black
– He has long hair
– He has lots of energy
– Quantitative data is numerical information (numbers).
• Example:
– He has 4 legs
– He has 2 brothers
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 5
Data (Cont…)
• Data is one of the most important resources of any
organisation.
• Without data and the ability to process it, organisations
could not survive.
• Data must be kept in such a manner so that it can be usable
easily.
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 6
Data (Cont…)
• Computer data is information processed or stored by a
computer. This information may be in the form of text
documents, images, audio clips, software programs, or
other types of data.
• Example
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 7
Managing the Data
• Data management ensures that the data is:
– Available
– Current
– Accurate
– Secure
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 8
Data and Database
• Databases and database technology have a major impact
on the growing use of computers. It is fair to say that
databases play a critical role in almost all areas where
computers are used, including business, electronic
commerce, engineering, medicine, genetics, law, education,
and library science.
• A database is a collection of related data. Data is raw facts
that can be recorded and that have implicit meaning.
– For example, consider the names, telephone numbers, and
addresses of the people you know. You may have recorded this data
in an indexed address book or you may have stored it on a hard
drive, using a personal computer and software such as Microsoft
Access or Excel. This collection of related data with an implicit
meaning is a database.
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 9
Data and Database (Cont…)
• we may consider the collection of words that make up this
slide of text to be related data and hence to constitute a
database. However, the common use of the term database
is usually more restricted. A database has the following
implicit properties:
– A database represents some aspect of the real world.
– A database is a logically coherent collection of data with some
inherent meaning.
– A database is designed, built, and populated with data for a specific
purpose. It has an intended group of users and some preconceived
applications in which these users are interested.
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 10
Data and Database (Cont…)
• In other words, a database has some source from which
data is derived, some degree of interaction with events in
the real world, and an audience that is actively interested in
its contents. The end users of a database may perform
business transactions (for example, a customer buys a
camera) or events may happen (for example, an employee
has a baby) that cause the information in the database to
change. In order for a database to be accurate and reliable
at all times, it must be a true reflection of the real world that
it represents; therefore, changes must be reflected in the
database as soon as possible.
• A database can be of any size and complexity.
• An example of a large commercial database is
Amazon.com.
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 11
Problems with the Traditional File
Environment
• Single Purpose Systems- single isolated files of records, no
link between one file and another.
• Data Redundancy – duplicated data stored in more than one
location
• Data Confusion- inconsistent data
• Program-Data Dependence – access to a particular file
depends on the program that created it
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 12
Human Resources
Staff data
Flat File System
Sales & Marketing
Sales Data
Separate files for each function.
Staff ID 2345321

Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Item Sold HRX1243
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Price $5.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Towel Rail
Price $35.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Vanity
Price $235.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID Name Item Sold HRX1243
Bath Mat
Price $5.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321

Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Item Sold HRX1243
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Price $5.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Towel Rail
Price $35.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Vanity
Price $235.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID Name Item Sold HRX1243
Bath Mat
Price $5.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 13
Flat File System (Cont…)
Data Redundancy – duplicated data stored in more than one location
Human Resources
Staff data
Sales & Marketing
Sales Data

Name Dave Dodgy
Address 22 Nut Dr.
Tullamarine
Position General
Manager
Salary $92,154.50
Address 27 Nut Dr.
Tullamarine
Position Sales AssistanSalary $41,126.20
Staff ID 2345321
Name Dora Dodgy
Address 27 Nut Dr.
Tullamarine
Position Sales
Assistant
Salary $41,126.20
taff ID 2345322
Name Don Dodgy
Address 23 Nut Dr.
Tullamarine
Position Cleaner
Salary $32,136.50
Staff ID 2345323
ddress Nut Dr.
Tullamarine
Position HRM
Manager
Salary $62,372.50
taff ID 2345323
Name Freda Nurk
Address 23 Nut Dr.
Tullamarine
Position HRM
Manager
Salary $62,372.50
Staff ID 2345324
Name Fred Nurk
Adress 23 Nut Dr.
Tullamarine
Position Sales
Manager
Slary $72,136.50
Staff ID 2345323
Name Freda Nurk
Item Sold HRX1241
Mirror
Price $81.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Name Freda Nurk
Item Sold HRX1243
Bathtub
Price $781.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345323
Name Freda Nurk
Item Sold HRX1243
Sunlamp
Price $78.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Name Freda Nurk
Item Sold HRX1243
Sunlamp
Price $78.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Name Freda Nurk
Item Sold HRX1243
Towel Rail
Price $35.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Name Freda Nurk
Item Sold HRX1243
Vanity
Price $235.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Name Freda Nurk
Item Sold HRX1249
Bath Mat
Price $5.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 14
Flat File System (Cont…)
Data Redundancy – duplicated data stored in more than one location
Human Resources
Staff data
Sales & Marketing
Sales Data

Name Dave Dodgy
Address 22 Nut Dr.
Tullamarine
Position General
Manager
Salary $92,154.50
Address 27 Nut Dr.
Tullamarine
Position Sales AssistanSalary $41,126.20
Staff ID 2345321
Name Dora Dodgy
Address 27 Nut Dr.
Tullamarine
Position Sales
Assistant
Salary $41,126.20
taff ID 2345322
Name Don Dodgy
Address 23 Nut Dr.
Tullamarine
Position Cleaner
Salary $32,136.50
Staff ID 2345323
ddress Nut Dr.
Tullamarine
Position HRM
Manager
Salary $62,372.50
taff ID 2345323
Name Freda Nurk
Address 23 Nut Dr.
Tullamarine
Position HRM
Manager
Salary $62,372.50
Staff ID 2345324
Name Fred Nurk
Adress 23 Nut Dr.
Tullamarine
Position Sales
Manager
Slary $72,136.50
Staff ID 2345323
Name Freda Nurk
Item Sold HRX1241
Mirror
Price $81.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Name Freda Nurk
Item Sold HRX1243
Bathtub
Price $781.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345323
Name Freda Nurk
Item Sold HRX1243
Sunlamp
Price $78.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Name Freda Nurk
Item Sold HRX1243
Sunlamp
Price $78.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Name Freda Nurk
Item Sold HRX1243
Towel Rail
Price $35.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Name Freda Nurk
Item Sold HRX1243
Vanity
Price $235.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Name Freda Nurk
Item Sold HRX1249
Bath Mat
Price $5.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Data Confusion – inconsistent data – Data Integrity is challenged
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 15
Flat File System (Cont…)
Program-Data Dependence: – Access to a particular file depends on the program that created it
Limited Data Sharing
Human Resources
Staff data
Sales & Marketing
Sales Data
Staff ID 2345319
Name Dave Dodgy
Address 22 Nut Dr.
Tullamarine

Staff ID 2345320
Name Dan Dodgy
Address 27 Nut Dr.
Staff ID 2345321
Name Dora Dodgy
Staff ID 2345322
Staff ID 2345323
Staff ID 2345323
Name Freda Nurk
Item Sold HRX1241
Mirror
Price $81.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Name Freda Nurk
Item Sold HRX1243
Bathtub
Price $781.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Name Freda Nurk
Item Sold HRX1243
Sunlamp
Price $78.00
Customer Name Joe Bloggs
Address 15 Sunny St
Sunshine
Staff ID 2345321
Name Freda Nurk
Item Sold HRX1243
Towel Rail
Price $35.00
Customer Name Joe Bloggs
Address 15 Sunny St

Staff ID 2345321
Name Freda Nurk
Item Sold HRX1243
Vanity
Price $235.00
Customer Name Joe Bloggs
Address 15 Sunny St
Staff ID 2345321
Name Freda Nurk
Item Sold HRX1249
Bath Mat
Price $5.00
Customer Name Joe Bloggs
Sunshine
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 16
Traditional File Environment: Other
Problems
• Lack of Flexibility
– Traditional systems can only deliver the reports that are designed into them.
– Reacting to changing needs is problematic.
• Poor Security
– Little control or management of data,
– Access may be out of control.
– No way of knowing who is accessing or even making changes to the
organisation’s data.
• Lack of Data Sharing and Availability
– Information in different files cannot be related to one another.
– Not easy for people to obtain information.
– Information cannot flow freely across different functional areas of the
organisation.
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 17
The Hierarchy of Data
• Database: A group of tables, connected together. It might
be the entire set of the organisation’s data.
• Table: A subset of a database. Typically it’s a logical thing
or event, such as student (in a school’s database), or
transaction (in a shop’s database)
• Record: Each table has one or more records, also called
rows. For example, each student in a student file would
have their own student record
• Field: Each table has several fields. Other names are
attributes and columns. An entity has several fields. They
are a characteristic of an entity e.g. a student’s name or
address.
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 18
The Hierarchy of Data (Cont…)
• Byte: 8 bits e.g. 10101011 and is a single character or
instruction (or part thereof), such as a letter, number, or
symbol. Today’s computers accept and process 8 byte
chunks at a time.
• Bit: A 1 or 0. The smallest unit of data a computer can
handle. Everything in a computer is stored as 0’s and 1’s.
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 19
The Hierarchy of Data (Cont…)
• Database
• Entity/File
• Record
• Column/field
• Byte (approx. 1 character)
• Bit 0
01001010
(Letter J in Ascii)
John Stewart
(Name field)
Name Course Date Grade
John
Stewart
IS101 04-06-18 B
Name Course Date Grade
John
Stewart
IS101 04-06-18 B
Course File Anna IS101 04-06-18 A
Course File Financial File
Personal History File
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 20
What is a DBMS?
• It is a system for
– storing,
– organising,
– processing and
– retrieving
• Large collections of data
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 21
Database Management System
• The phrase “Database Management System” (DBMS)
suggests more than just “Database” software. But in fact, all
software we call database software (such as Microsoft
Access and Oracle) are DBMS’s.
• A DBMS is an application that interacts with the user, other
applications, and the database itself to capture and analyse
data. To say it another way, a DBMS is the software that
permits an organisation to
– centralize data,
– manage it efficiently, and
– provide access to the stored data by application programs
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 22
Database Management Systems (Cont…)
• There are many choices
– MS Access, File Maker Pro, FoxPro, etc. – for small businesses and
home users
– MS SQL Server
• Enterprise Edition – with all the security, size, and functionality
power
• Standard Edition – for large enterprises with minimal IT
infrastructure
• Express – a free edition with basic capabilities
– ERP software –contain a database at their core. All other data
management interfaces and software needed by different
departments are attached to it in modules. Allows for full integration
and consistency across the enterprise. e.g. SAP, Sage, Oracle
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 23
The DBMS as the Interface
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 24
Advantages of a DBMS
• Reduced Data Redundancy
– Each item of data is held in only one place.
– All applications share the same data set.
• Restricting Unauthorized Access
– When multiple users share a database, it is likely that some users will not be
authorized to access all information in the database. For example, financial
data is often considered confidential, and hence only authorized persons are
allowed to access such data. In addition, some users may be permitted only
to retrieve data, whereas others are allowed both to retrieve and to update.
Hence, the type of access operation—retrieval or update—must also be
controlled.
• Providing Persistent Storage for Program Objects and Data
Structures
– Traditional database systems often suffered from the so-called impedance
mismatch problem, since the data structures provided by the DBMS were
incompatible with the programming language’s data structures. Objectoriented database systems typically offer data structure compatibility with
one or more object-oriented programming languages.
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 25
Advantages of a DBMS (Cont…)
• Permitting Inferencing and Actions Using Rules
– Some database systems provide capabilities for defining deduction rules for
inferencing new information from the stored database facts. Such systems
are called deductive database systems. For example, there may be complex
rules in the miniworld application for determining when a student is on
probation. These can be specified declaratively as rules, which when
compiled and maintained by the DBMS can determine all students on
probation. In a traditional DBMS, an explicit procedural program code would
have to be written to support such applications.
• Providing Multiple User Interfaces
– Because many types of users with varying levels of technical knowledge use
a database, a DBMS should provide a variety of user interfaces. These
include query languages for casual users; programming language interfaces
for application programmers; forms and command codes for parametric
users; and menu-driven interfaces and natural language interfaces for standalone users.
• Representing Complex Relationships Among Data
– A database may include numerous varieties of data that are interrelated in
many ways.
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 26
Advantages of a DBMS (Cont…)
• Enforcing Integrity Constraints
– The simplest type of integrity constraint involves specifying a data type for
each data item.
• Providing Backup and Recovery
– A DBMS must provide facilities for recovering from hardware or software
failures. The backup and recovery subsystem of the DBMS is responsible for
recovery. For example, if the computer system fails in the middle of a
complex update program, the recovery subsystem is responsible for making
sure that the database is restored to the state it was in before the program
started executing. Alternatively, the recovery subsystem could ensure that
the program is resumed from the point at which it was interrupted so that its
full effect is recorded in the database.
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 27
Other Advantages of a DBMS
• Increased Speed – Database Management system is
optimised for Searching & Retrieval
• Easier modification & Updating – New applications, reports &
Queries can be added without disrupting existing
applications
• Better access to data and information – All users can be
given access to all data, or access can be sliced and diced
in more complex/role sensitive ways
• Standardisation of data access – All applications use the
same style of interface.
• Provide for data security – Access to sensitive data can be
restricted to authorised users. Access can be centrally
managed.
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 28
Results of using Database Approach
• Potential for Enforcing Standards
– The database approach permits the DBA to define and enforce standards
among database users in a large organization. This facilitates
communication and cooperation among various departments, projects, and
users within the organization. Standards can be defined for names and
formats of data elements, display formats, report structures, terminology,
and so on. The DBA can enforce standards in a centralized database
environment more easily than in an environment where each user group has
control of its own files and software.
• Reduced Application Development Time
– Designing and implementing a new database from scratch may take more
time than writing a single specialized file application. However, once a
database is up and running, substantially less time is generally required to
create new applications using DBMS facilities. Development time using a
DBMS is estimated to be one-sixth to one-fourth of that for a traditional file
system.
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 29
Results of using Database Approach (Cont…)
• Flexibility
– It may be necessary to change the structure of a database as requirements
change. For example, a new user group may emerge that needs information
not currently in the database. In response, it may be necessary to add a file
to the database or to extend the data elements in an existing file.
• Availability of Up-to-Date Information
– A DBMS makes the database available to all users. As soon as one user’s
update is applied to the database, all other users can immediately see this
update. This availability of up-to-date information is essential for many
transaction-processing applications, such as reservation systems.
• Economies of Scale
– The DBMS approach permits consolidation of data and applications, thus
reducing the amount of wasteful overlap between activities of dataprocessing personnel in different projects or departments. This enables the
whole organization to invest in more powerful processors, storage devices,
or communication gear, rather than having each department purchase its
own (weaker) equipment. This reduces overall costs of operation and
management.
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 30
When not to use a DBMS
• In spite of the advantages of using a DBMS, there are a few
situations in which a DBMS may involve unnecessary
overhead costs that would not be incurred in traditional file
processing. The overhead costs of using a DBMS are due to
the following:
– High initial investment in hardware, software, and training.
– The generality that a DBMS provides for defining and processing
data.
– Overhead for providing security, concurrency control, recovery, and
integrity functions.
ITDA1001 [Lesson 1] Copyright © 2018 VIT, All Rights Reserved 31
When not to use a DBMS (Cont…)
• Therefore, it may be more desirable to use regular files
under the following circumstances:
– Simple, well-defined database applications that are not expected to
change at all.
– Stringent, real-time requirements for some application programs that
may not be met because of DBMS overhead.
– Embedded systems with limited storage capacity, where a generalpurpose DBMS would not fit
– No multiple-user access to data
ITAP1001 Lesson2 Copyright © 2018 VIT, All Rights Reserved 32
Summary
• Revision of Key Concepts
• Home Work
– Lesson 1 – Activity 1 (Lesson_1 Activity.docx)
• Questions and Answer

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