1. INTRODUCTION TO DATABASES
Chapter 1
INTRODUCTION TO DATABASES
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2. Chapter 1 - Objectives Some common uses of database systems.
Characteristics of file-based systems.
Problems with file-based approach.
The 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.
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3. Database Concepts Data: numbers, strings, text, date, time, timestamp,
is a meaningless static value.
Known facts that can be recorded and have an implicit meaning. ex)What does 3421 means?
facts about entities
Person's name, Phone, address, , 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 …

4. Database Concepts Information:
is the data you process in a manner that makes it meaningful. Information can be provided only if proper data exists.
Data VS information
Data itself has no meaning without meta data which describes data
For example : , 28761, 153
Data does 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.
Data is what you store in database.
Information is what you retrieve from a database.

5. Database Concepts Database (DB): Two examples
is a collection of related persistent data. Can be generated & maintained manually or automatically
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/ city – string, length<15
Sara , Abha , 01/03/ birth – date, format DD/MM/YY
Two examples
all data required for the management of student records in a university.
all data required for the management of books and borrowers in a library.

6. Database Concepts Database Management System (DBMS)
a software system that enables users to create, maintain, and query the database
Most DBMSs now have facilities that make data access fast, reliable, secure and easy
Example DBMSs
Oracle
MS Access
MySQL

7. Database Concepts Database application:
a program that interacts with the database at some point in it’s execution .
built on top of DBMS
to satisfy end users special requirements and preference
A database application is usually implemented using a Database Management System (DBMS).
Database System (DBS) is (DB + Software (DBMS + Application program)).

8. (DB +Software (DBMS + Application program) )
Database Concepts
Database System
Database System:
is a collection of data and the programs interacts with the database. OR
the DBMS software together with the data itself. Sometimes, the applications are also included.
(DB +Software (DBMS + Application program) )
To manage large amounts of data
Efficiently
Reliably
Securely
conveniently

9. Database Environment DBS Application Programs DBMS Query Process
Data Access
Meta-Data
Database

10. Types of Databases Numeric and Textual Databases Multimedia Databases
Geographic Information Systems (GIS)
Data Warehouses
Real-time and Active Databases
Lecture1

11. Examples of Database Applications
Purchases from the supermarket
Purchases using your credit card
Booking a holiday at the travel agents
Using the local library
Studying at university
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12. File-Based Systems
Collection of application programs that perform services for the end users (e.g. reports).
Each program defines and manages its own data.
File
handling
Data
Entry
User 1
File Definition
Application Program 1
File1
File
handling
Data
Entry
User 2
File Definition
Application Program 2
File 2
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13. Limitations of File-Based Approach
Separation and isolation of data
Each program maintains its own set of data.
Users of one program may be unaware of potentially useful data held by other programs.
Duplication of data
Same data is held by different programs.
Duplication wasteful, it cost time and money.
Wasted space and potentially different values and/or different formats for the same item.
It can lead to loss of data integrity, the data will not be consistent.
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14. Limitations of File-Based Approach
Data dependence (program_data dependence)
File structure is defined in the program code.
The changes to an existing structure are difficult to make.
Incompatible file formats
Programs are written in different languages, and so cannot easily access each other’s files.
This can be time consuming and expensive.
Fixed Queries/Proliferation of application programs
Programs are written to satisfy particular functions.
Any new requirement needs a new program.
214 MIS

15. Database Approach Arose because:
Definition of data was embedded in application programs, rather than being stored separately and independently.
No control over access and manipulation of data beyond that imposed by application programs.
Result:
the database and Database Management System (DBMS).
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16. Database
Shared collection of logically related data (and a description of this data), designed to meet the information needs of an organization.
The description of the data is known as the system catalog, ( data dictionary or meta_data- the data about data)
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17. Database Approach
Lecture1

18. Database Management System (DBMS)
A software system that enables users to define, create, maintain, and control access to the database.
(Database) application program: a computer program that interacts with database by issuing an appropriate request (SQL statement) to the DBMS.
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19. Database Management System (DBMS)
Major Relational DBMS vendors/products:
Oracle
MS Access
MySQL
DB2 by IBM

20. 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).
Lecture1

21. Main Characteristics of the Database Approach
Abstraction is the process of recognizing and focusing on important characteristics of a situation or object and leaving/filtering out the un-wanted characteristics of that situation or object
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 (external definition ) of the database. We can change the internal definition of an object without affecting the user of the object. 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.
Lecture1

22. 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 by letting users see the data in the way they want to see it.
Provide a level of security
Views provide a mechanism to customize the appearance of the database,
Present a consistent, unchanging picture of the structure of the database, even if the underlying database is changed
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23. Views view1 view2 Salary Age LName FName Staff_No LName FName Salary
Bno
LName
FName
Bno
Salary
DOB
Age
LName
FName
Staff_No
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24. 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.
Lecture1

25. the database management system (dbms)
A software system that enables users to define ,create, maintain and control access to the database.
Facilities:
It allow users to define the database usually through a Data Definition Language (DDL)
It allow users to access the data usually through a Data Manipulation Language (DML)
It provides controlled access to the database : security system, an integrity system, concurrency system, recovery control, and a user accessible catalog

26. Database Approach Data definition language (DDL):
DDL is a descriptive language for defining the database schema.
Permits specification of data types, structures and any data constraints.
All specifications are stored in the database.
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27. Database Approach Data manipulation language (DML):
DML is a language for retrieving and updating (insert, delete, and modify) the data in the DB.
General enquiry facility (query language) of the data.

28. Components of DBMS Environment
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29. Components of DBMS Environment
Hardware
Can range from a PC to a single mainframe ,to a network of computers.
Depends on the organization’s requirements and the DBMS used.
Software
DBMS, operating system, network software (if necessary) and also the application programs.
Data
Used by the organization the database contains operational data and the meta data. The structure of the database is called the schema.
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30. Components of DBMS Environment
Procedures
Instructions and rules that should be applied to the design and use of the database and DBMS.
The users of the database require documented procedures on how to use or run the system.
People
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31. Roles in the Database Environment
Data administration (DA)
Database Administrator (DBA)
Database Designers (Logical and Physical)
System Analysis
Application Programmers
Database Users (naive and sophisticated)
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32. Roles in the Database Environment
Communicate
Procedure
User
Requirement
Write
Write
DB Designer
System Analyst
Application
programmer
Design
Program
Manage
DBA
App
Program
DBMS
Use
Naïve End User DB
Use
Sophisticated End User
H/W

33. Database Users
System Analyst: Determine the user requirements and develop the system specifications.
Database Designers:
In a large database :Logical database designer and physical database designer
Logical database designer :responsible for defining the content, the structure, the constraints, and functions or transactions in the database.
Physical database designer decides how the logical database design is to be physically realized.
Application Programmer
Implement programs meet the end user needs
Test , debug , document, and maintain transactions
Lecture1

34. Database Users Data administrators: responsible for:
Management of data resource including database planning, development and maintenance.
Policies and procedures.
And conceptual /logical database design
Lecture1

35. Database Users Database administrators: responsible for:
Physical realization of the database including physical database design and implementation.
authorizing access to the database
coordinating and monitoring the DB use
acquiring software, and hardware resources
monitoring efficiency of operations.
Lecture1

36. 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 unaware of DBMS
They make up a large section of the end-user population.
They use previously well-defined functions ,entering simple commands or choosing options from a menu.
Examples: bank-tellers or reservation clerks.
Sophisticated : Forms requests in a database query language.
Lecture1

37. Advantages of DBMS Control of data redundancy Data consistency
More information from the same amount of data
Sharing of data
Improved data integrity
Improved security
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38. Disadvantages of DBMS Complexity Size
Cost (DBMS, Hardware, Staff, Training)
Performance
Higher impact of a failure
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