Transcript Database Management System

Database Management System
CCPS1533
Dr. Abdulsamad Ebrahim
Lecture 1
Introduction to Database Management
Learning Outcomes
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Grasp the definition of a database.
Get introduced to the main building blocks for a database.
Understand the requirements of database applications
Understand and explain basic database characteristics.
Appreciate how databases can be categorized based on size.
Terminology
• Data
Information to be manipulated,
stored, combined, analysed etc.
• Database
A collection of related information
stored in a structured format
• DBMS
Database management system. A
programs which lets you manage
information in databases
• Table
A single store of related information.
• A table consists of records, and each record is made up of a
number of fields
- Field Elementary piece of data
- Record
Set of fields
Database Definition
A database is an environment for:
• Storing a large amount of information in a structured way
• And allowing the rapid retrieval and update of information and
the combination of data in complex ways
This environment must be coherent, reliable and secure
Examples of database
applications
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Booking systems
Bank clients management,
Backend storage for an e-commerce web site,
Books and readers management in a library
Main building blocks for a
traditional database
• A field is the smallest granularity of information,
• A record is set of fields combining a number of data items
possibly of different types ,
• A file is a collection of records.
Database example
• A library in the real physical world contains books borrowed
by readers.
• A database supporting a library could logically maintain the
data related to a library as follows:
• A library file which is composed of a collection of:
- book
- reader and
- borrowing records
Book record
• Each book in the library can be represented in the database as
a:
book record
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which could be composed of the following fields:
title
authors
publisher and
publication date.
Book records in a library
database
Book identifier
Title
1
2
Authors
Publisher
Publication date
A Tale of Two Cities Charles Dickens
London: Chapman
& Hall
1859
For Whom the Bell
Tolls
Charles Scribner's
Sons
1940
Ernest Hemingway
Reader record
• Each reader who is a member of the library can be represented
by a:
reader record
which contains the following fields:
first name
last name
address
subscription date.
Reader records in a library
database
Reader
identifier
Firs tname Last name Address
subscription
date
1
John
Seaman
50 Dover
Street,
London
11/11/03
2
Barbara
James
22
06/07/99
Northbourne
Road,
London
Borrowing records
• Library borrowing can be represented by:
borrowing records
each of which can be composed of book :
identifier,
reader identifier,
start date and
end date.
Borrowing records in a
library database
Borrowing identifier Book identifier
Reader identifier
Start date
End date
1
2
2
07/09/10
11/12/10
2
1
1
01/06/10
07/08/10
Database Application
Requirements
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Presentation Requirement
• A graphical standard should be used to visualize the database
irrespective of the underlying computing technology used to
support the database.
• Example: consider a Library database which has book, author
and reader entities.
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It includes borrow and write actions.
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Such database can be graphically modeled as shown in
flowing Figure
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Data Creation/Modification Requirements
• Inserting new data to the database (e.g. inserting new books,
new readers, registering borrowing, etc.)
• To be able to modify and eventually deleting a set of data (e.g.
modifying the address of a reader, deleting a reader or a book)
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Interrogation Requirements
• An application should be able to query a database to:
- Retrieve data that meets certain conditions.
Examples of an application queries to a
library database could be:
• Information on every book in the database which has been
borrowed only by one reader.
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Information on readers with subscription date before
01/01/2000
• Information on a book written by Osama
borrowed by Khalid Jamal.
Ahmad
and
4. Accuracy / Consistency Requirements
• A database system must guarantee that data inserted and
manipulated by an application are kept accurate and consistent
without errors. For example:
• A book copy can never be borrowed by two readers at the
same time.
• The start date of borrowing must be before the end date
Database Characteristics
A number of main characteristics must be commonly found in
any database which include:
• A database is an integrated structure with semantic links
between its entities. Integrity constraints must be met while
data is manipulated to ensure data accuracy and consistency.
Security constraints must exist to manage database access.
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• Supporting data manipulation operations including data
insertion, deletion, updating and searching. Data insertion and
update must be coherent, shared, reliable and secure
Database Sizes
• Databases can be classified according to their size:
• Personal Database: this type of database is small in size
and usually used by a single user. It is usually installed on
a PC. The size of such database is 100KB- 100MB.
• Typical Professional Database: generally used by SMEs
(Small to Medium Enterprises). Their size varies between
100MB and 1TB.
• Very Large Database (VLDB): The size of such database
usually exceeds 1 TB.
Summary
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The definition of database notion.
The requirements of database applications.
The basic characteristics of a database.
Database types based on size.
Exercises
• What are the requirements of database applications
• Explain how fields, records and files are building blocks of a
database system.
• What is the size of a typical VLDB database
Thank You