Lecture1: Principles of Databases

Prepared by L. Nouf Almujally

1

Ref. Chapter1

Chapter1 - Objectives

• Meaning of the term database.• Meaning of the term Database Management System

(DBMS).• Major components of the DBMS environment.• Users involved in the DBMS environment.• Advantages and disadvantages of DBMSs.

Lect

ure

1

2

Data• Data: Known facts that can be recorded and have an

implicit meaning. ex)What does 3421 means?• facts about entities • Person's name, Phone, address, email, picture, …• Student's ID, name, subjects taken, results,…• Product's name, description, manufacturer, price,…• Book's publisher, author, title,…

• facts about relationships• BADER lives in Riyadh• Nora bought a book from university books shop on

01/03/11• Notice the different types of data

• numbers, strings, text, date, time, timestamp, • Text, picture, audio, video, graphics …

Lect

ure

1

3

Data versus InformationData itself has no meaning without meta data which describes

data For example :

1012674, 28761, 153Does not give us any information, but knowing the meta data

that explains data : Staff_ID, Phone Number, room number

Information : is the data you process in a manner that makes it meaningful.

Lect

ure

1

4

Staff_ID Phone Number room number1012674 28761 153

DatabaseDatabase

A collection of logically related data, including metadata - ”data about data”, that describes data

Data: name city birth Metadata: name - string, length<10 Khaled Dammam 01/01/70 city – string, length<15 Sara Abha 01/03/01 birth – date, format DD/MM/YY

Data is what you store in databaseInformation is what you retrieve from database

Two examplesall data required for the management of student records in a university.all data required for the management of books and borrowers in a

library.

Lect

ure

1

5

Types of Databases

Numeric and Textual DatabasesMultimedia DatabasesGeographic Information Systems (GIS)Data WarehousesReal-time and Active Databases Le

cture

1

6

Example of a Database(with a Conceptual Data Model)Mini-world: Some part of the real world about

which data is stored in a database. Mini-world for the example: Part of a UNIVERSITY

environment.

Some mini-world entities:STUDENTsCOURSEsSECTIONs (of COURSEs)Grade ReportPrerequiests

Lect

ure

1

7

Lect

ure

1

8

Lect

ure

1

9

Example of a Database(with a Conceptual Data Model)Some mini-world relationships:

SECTIONs are of specific COURSEsSTUDENTs take SECTIONsCOURSEs have prerequisite COURSEsINSTRUCTORs teach SECTIONsCOURSEs are offered by DEPARTMENTsSTUDENTs major in DEPARTMENTs

Lect

ure

1

10

Lect

ure

1

11

Database Management Systems

Database Management System (DBMS) A software system that enables users to

create, maintain, and query the databaseMost DBMSs now have facilities that make

data access fast, reliable, secure and easy

Example DBMSsOracle MS AccessMySQL

Lect

ure

1

12

Functions of a DBMS

• Data Storage, Retrieval, and Update.• Storing data definition in the form of data dictionary• Transaction Support • Transaction: executing program or process that

includes one or more database accesses, such as reading or updating of DB record

• Concurrency Control Services.• Recovery Services.• Security protection against unauthorized access.• Maintain and develop the database system

Lect

ure

1

13

Application programs

• Database Application : is a collection of data and the programs that allow the manipulation of these data to meet the information needs by an enterprise.• built on top of DBMS• to satisfy end users special requirements and

preference

Lect

ure

1

14

Examples of Database Applications

• Purchases from the supermarket• PNU Student Registration • PNU Library• Saudi Airline Reservation• Purchases using your credit card • Booking a holiday at the travel agents• Using the Internet

Lect

ure

1

15

Database SystemDatabase System: The DBMS software together with

the data itself. Sometimes, the applications are also included.

(DB + DBMS + Application program)

To manage large amounts of dataEfficientlyReliablySecurelyconveniently

Lect

ure

1

16

Lect

ure

1

17

Database Approach

Lect

ure

1

18

Main Characteristics of the Database Approach

• Self-describing nature of a database system: A DBMS catalog stores the description of the database. The description is called meta-data). This allows the DBMS software to work with different databases.

• Insulation between programs and data: Called program-data independence. Allows changing data storage structures and operations without having to change the DBMS access programs (application program).

Lect

ure

1

19

Main Characteristics of the Database Approach

• Data Abstraction: A data model is used to hide storage details and present the users with a conceptual view of the database.

• Support of multiple views of the data: Each user may see a different view of the database, which describes only the data of interest to that user.

Lect

ure

1

20

Views

• Allows each user to have his or her own view of the database.• A view is essentially some subset of the

database. • Benefits:• Reduce complexity• Provide a level of security• Present a consistent, unchanging picture of the

structure of the database, even if the underlying database is changed 21

Pearson Education © 2009

Main Characteristics of the Database Approach

Sharing of data and multiuser transaction processing : allowing a set of concurrent users to retrieve and to update the database. Concurrency control within the DBMS guarantees that each transaction is correctly executed or completely aborted.OLTP (Online Transaction Processing) is a major part of

database applications.

Lect

ure

1

22

Advantages of Using the Database Approach

• Controlling redundancy in data storage and in

development and maintenance efforts.

• Sharing of data among multiple users.

• Restricting unauthorized access to data.

• Providing persistent storage for program Objects

• Providing Storage Structures for efficient Query

Processing

Lect

ure

1

28

Advantages of Using the Database Approach

• Providing backup and recovery services.• Providing multiple interfaces to different

classes of users.• Representing complex relationships among

data.• Enforcing integrity constraints on the

database.

Lect

ure

1

29

Disadvantages of Database Approach

• Complexity• Cost of DBMS• Additional hardware costs• Performance• Higher impact of a failure Le

cture

1

25

Components of DBMS Environment

• Hardware• Can range from a PC to a network of computers.

• Software• DBMS, operating system, network software (if

necessary) and also the application programs.• Data• Procedures• Instructions and rules that should be applied to the

design and use of the database and DBMS.• People

Lect

ure

1

26

Components of DBMS Environment

27

Lect

ure

1

28

DBMSApp

Program

DB

UserRequirement

Procedure

DBA

Naïve End User

Applicationprogrammer

DB DesignerSystem Analyst

Sophisticated End User

H/W

Design

Communicate

Manage

Write Write

Program

Use

Use

Database Users

Database Users

• System Analyst: Determine the user requirements and develop the system specifications.

• Database Designers:• responsible for defining the content, the structure,

the constraints, and functions or transactions against the database.

• Application Programmer• Implement programs meet the end user needs• Test , debug , document, and maintain transactions

Lect

ure

1

25

Database Users

• Database administrators: responsible for:• authorizing access to the database• coordinating and monitoring the DB use• acquiring software, and hardware resources• monitoring efficiency of operations. Le

cture

1

25

Database Users• End-users: they use the data for queries, reports and

some of them actually update the database content.• Categories of End-users:

Naïve : (Queries / modifies data)- they make up a large section of the end-user

population.- They use previously well-defined functions in the

form of “canned transactions” against the database.

- Examples: bank-tellers or reservation clerks.Sophisticated : Forms requests in a database query

language.

Lect

ure

1

25

Lect

ure

1

32

References

• “Database Systems: A Practical Approach to Design, Implementation and Management.”Thomas Connolly, Carolyn Begg.5th Edition, Addison-Wesley, 2009.

• Fundamentals of Database Systems", Ramez Elmasri, Shamkant B. Navathe, Addison Wesley, The Latest Edition.

Lect

ure

1

33