LECTURE#27
YASMIN AFZAAL

 Introduction and Purpose of Databases
 Databases vs. File System
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DATA
 What is Data?
 In simple words data can be facts related to any object
in consideration.
 For example your name, age, height, weight, etc. are
some data related to you.
 A picture , image , file , pdf etc. can also be considered
data.
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WHAT IS A DATABASE
 Database is a systematic collection of data.
Databases support storage and manipulation of
data. Databases make data management easy.
For examples:
 An online telephone directory would definitely use
database to store data pertaining to people, phone
numbers, other contact details, etc.
 Electricity service provider is obviously using a
database to manage billing , client related issues, to
handle fault data, etc.
 Facebook also needs to store, manipulate and present
data related to members, their friends, member
activities, messages, advertisements and lot more.
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APPLICATIONS OF DBMS
 Banking : for customer information, accounts and loans and
banking transactions.
 Universities : for student registrations and grades.
 Online shopping : Everyone wants to shop from home.
Everyday new products are added and sold only with the help
of DBMS. Purchase information, invoice bills and payment, all
of these are done with the help of DBMS.
 Airlines : for reservations and schedule information.
 Credit card transactions : for purchases on credit cards and
generation of monthly statements.
 Library Management System : maintain all the information
relate to book issue dates, name of the book, author and
availability of the book.
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CONT.…
 Telecommunications : for keeping records of call
made, generating monthly bills, maintaining balances on
prepaid calling cards.
 Sales : for customer, product and purchase information.
 Finance : for storing information about holdings, sales,
and purchases of financial instruments such as stocks
and bonds.
 Manufacturing : for management of supply chain and
for tracking production of items in factories, inventories
of items and orders for items.
 Human Resource : for information about employees,
salaries, payroll taxes and benefits.
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WHAT IS A DATABASE MANAGEMENT SYSTEM
(DBMS)?
 A database-management system (DBMS) is
a computer-software application that interacts
with end-users, other applications, and the
database itself to capture and analyse data.
 A general-purpose DBMS allows the definition,
creation, querying, update, and administration of
databases.
 It also helps to control access to the database.
 Database Management Systems are not a new
concept and as such had been first implemented in
1960s.
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DATABASE LANGUAGES
 Database is built and maintained by using a database
programming language.
 Database languages are used for read, update and
store data in a database.
 There are several such languages that can be used for
this purpose;
 Microsoft Access is one of the most popular database
platforms on the market today.
 SQL (Structured Query Language) is the most
common database language and is used by most
databases today. We use SQL for a database for a
medium to large business.
 Server databases like MySQL, Microsoft SQL Server,
and Oracle are enormously powerful 8

WHAT IS THE STRUCTURE OF A DATABASE?
 A database is made up of tables that contain
columns (field) and rows (records) can be designed
to hold a specific type of data, such as a number,
text or a date.
 Data is separated by categories into tables in order
to avoid duplication.
 For example, a business might have a table for
Employees, one for Customers and another for
Products.
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DATABASE COMPONENTS
 A database is made up of several main components.
 Schema - A database contains one or more schemas, which
is basically a collection of one or more tables of data.
 Table - Each table contains multiple columns, which are
similar to columns in a spread sheet. A table can have as little
as two columns and as many as one hundred or more
columns, depending on the type of data being stored in the
table.
 Column - Each column contains one of several types of data
or values, like dates, numeric or integer values, and
alphanumeric values (also known as varchar).
 Row - Data in a table is listed in rows, which are like rows of
data in a spread sheet. Often there are hundreds or
thousands of rows of data in a table.
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A DATABASE….
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WHAT CAN A DATABASE DO?
 On the surface, a database might seem much like a
spread sheet; it has data arranged in columns and rows.
But that is where the similarity ends because a database
is far more powerful.
 If the database is relational. This means that you can
create relationships between tables.
 if you linked a Customers table with an Orders table, you could
find all purchase orders from the Orders table that a single
customer from the Customers table ever processed,
 A database has broad searching functionality.
 For example, a sales department could quickly search for and find
all sales personnel who had achieved a certain amount of sales
over a particular time period.
 A database can update records in bulk – even millions
or more records.
 For example, if you wanted to add new columns or apply a data
patch of some sort. 12

CONT..
 A database can perform complex aggregate calculations
across multiple tables.
 For example, you could list expenses across multiple retail
outlets, including all possible sub-totals, and then a final total.
 A database can enforce consistency and data integrity,
which means that it can avoid duplication and ensure
data accuracy through its design and a series of
constraints.
 A database will include forms so that users can input or
edit data. In addition, it will have the facility to generate
reports from the data. A report is simply the answer to a
question, called a query in database-speak. For
instance, you might query the database to find out a
company's gross income over a particular time period.
The database will return to you the report with your
requested information. 13

DATABASES VS. FILE SYSTEM
 A Database Management System (DMS) is a
combination of computer software, hardware, and
information designed to electronically manipulate data
via computer processing.
 Two types of database management systems are
DBMS’s and FMS’s.
 A File Management System (FMS) is a Database
Management System that allows access to single files
or tables at a time. FMS’s accommodate flat files that
have no relation to other files.
 The FMS was the predecessor for the Database
Management System (DBMS), which allows access to
multiple files or tables at a time.
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 A database management system coordinates both the
physical and the logical access to the data, whereas a file-
processing system coordinates only the physical access.
 A database management system is designed to allow
flexible access to data (i.e. queries), whereas a file-
processing system is designed to allow predetermined
access to data (i.e. compiled programs).
 A database management system is designed to coordinate
multiple users accessing the same data at the same time. A
file-processing system is usually designed to allow one or
more programs to access different data files at the same
time. In a file-processing system, a file can be accessed by
two programs concurrently only if both programs have read-
only access to the file.
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CONT.…
 Redundancy( duplication of data) is control in
DBMS, but not in file system.
 Unauthorized access is restricted in DBMS but not
in the file system.
 DBMS provide back up and recovery whereas data
lost in file system can't be recovered.
 DBMS provide multiple user interfaces. Data is
isolated in file system.
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 Lets explore some data base systems.
 Student database
 A shop database etc.
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