1. Database Design Chapter-1- Basic Concepts Reference:
Prof. Mona Mursi Lecture notes
Dr.Lilac Safadi Lecture notes
Feb 26,2008
Fatimah Alakeel

2. Database Concepts
Data is a meaningless static value. What does 3421 means?
Information is the data you process in a manner that makes it meaningful. Information can be provided only if proper data exists.
A database (DB) is a collection of related persistent data. Can be generated & maintained manually or automatically
Data is what you store in database.
Information is what you retrieve from a database.
A database application is a collection of data and the programs that allow the manipulation of these data to meet the information needs of an enterprise
Feb 26,2008
Fatimah Alakeel

3. Database Application: Examples
KSU Library
Saudia Airline Reservations
Car rental DB
A DB for all schools in Riyadh
Feb 26,2008
Fatimah Alakeel

4. Database Properties
Represents the real world (miniworld, Universe of Discourse UoD)
Logically coherent collection of data.
Designed, built, populated with data for a specific purpose. It has an intended group of users and their applications.
Can be of any size and any degree of complexity.
Can be generated and maintained manually or using a computer. A computerized DB can be created by:
A Group of application programs
Or by Database Management System (DBMS)
Feb 26,2008
Fatimah Alakeel

5. The Data in the DB are Shared by multiple users
Stored less redundantly
Made independent of applications
Organized
Feb 26,2008
Fatimah Alakeel

6. Database Management System (DBMS)
A collection of programs that enables the users to create and maintain a database.
A general- purpose software system that facilitates the process of :
Defining (specifying data types, structures and constraints)
Constructing (storing the data on a storage medium controlled by DBMS)
Manipulating (querying, update, generate reports)
And Maintaining
The database for various applications .
Feb 26,2008
Fatimah Alakeel

7. DBS Environment DBS Application Programs DBMS Query Process
Data Access
Meta-Data
Database
Database System = Database + DBMS
Feb 26,2008
Fatimah Alakeel

8. DBMS Capabilities & Responsibilities
Control redundancy.
Access a large amount of data efficiently.
Support a data model in which is conceptually captured.
Support HLL to define, access and manipulate data.
Provide correct access to data by multiple users.
Provide multiple users views.
Maintain data integrity.
Protect data.
Recover from failures.
Feb 26,2008
Fatimah Alakeel

9. Database Management System
Major Relational DBMS vendors/products
Paradox by Corel
dBase, Clipper
FoxPro, Access & SQL Server by MS
MySQL
DB2 by IBM
Oracle, Sybase, Informix
Feb 26,2008
Fatimah Alakeel

10. Advantages of Database Systems over Paper-Based Systems
Compactness
Speed
Less of hard work
Currency
Feb 26,2008
Fatimah Alakeel

11. File-Based Systems (FBS)
FBS is a collection of application programs that perform tasks where each program defines and manages its own data.
File
handling
Data
Entry
User 1
File Def
Application Program 1
File1
File
handling
Data
Entry
User 2
File Def
Application Program 2
File 2
Feb 26,2008
Fatimah Alakeel

12. File-Based Systems (FBS)
The limitations of the FBS approach attributed to two factors:
The definition of data is embedded in the application programs
There is no control over the access & manipulation of data beyond the imposed by the application program
Feb 26,2008
Fatimah Alakeel

13. Differences between Files and a database
A database is self contained
A database contains the description (system catalog OR data dictionary OR meta data).
Feb 26,2008
Fatimah Alakeel

14. File-Based Systems (FBS) Disadvantages
Data Redundancy & Inconsistency
Waste of space
Cost of update
Risk of inconsistency
Concurrent Access Anomalies
Security Problems
Integrity Problems
Logical Data Dependence
Limited data sharing
Inflexibility to access data
Poor enforcement of standards
Physical Data Dependence
Low programmer productivity
Excessive program maintenance
Feb 26,2008
Fatimah Alakeel

15. Database Systems Advantages
Minimal Data Redundancy
Logical Data Dependence
Data sharing
Multiple access path to data
User views
Physical Data Dependence
Application development is easy
Less maintenance
Good performance
Uniform control for security, privacy and integrity.
Feb 26,2008
Fatimah Alakeel

16. Database Systems Advantages
5- Potential for enforcing standards
DBA enforce standards for names and formats of data, display formats, reports structures.
6- Reduced application development time
Ex: Retrieval of data or printing a new report
7- Flexibility
Change the structure without affecting the data and application programs
8- Up-to-date information is available
All users access the DB. Once they save the changes the DB id available to the other users
9- Economies of scale
DBMS permits unification of data and application => reduce the cost of operation and management
Feb 26,2008
Fatimah Alakeel

17. Database Systems (DBS)
DBS is a single large repository of data, defined once & used by many application programs.
Data
Entry
User 1
Application Program 1
DBMS
Data
Entry
Database
User 2
Application Program 2
Feb 26,2008
Fatimah Alakeel

18. Characteristics of DB Approach
Self –Describing nature of a database system
The database system contains:
Database
Complete definition of the DB structure and constraints (catalog)
DBMS
Meta- Data
Database
Catalog
The DBMS works with any number of database applications
Feb 26,2008
Fatimah Alakeel

19. Characteristics of DB Approach
Program-Data Independence
In file based systems the structure of data files is embedded in the access programs => any change to the structure may require changing all accessing programs
In DBMS any change in the structure does not require changing the access programs because the structure is stored in the DBMS catalog. => this is called program-data independence.
Feb 26,2008
Fatimah Alakeel

20. Characteristics of DB Approach
Data Abstraction
DBMS provides a conceptual representation of the data => no much details about how the data is stored and how the operations are implemented.
There are different levels of abstraction.
Feb 26,2008
Fatimah Alakeel

21. Characteristics of DB Approach
Describe some parts of the databse
Users
Data Abstraction
View 1
View 2
View 3
View N
……..
Conceptual Level
What data is stored and how its interrelated (tables or tree)
Database Administrators
How the data is stored in the physical media (files of records or structs) Implementers
Physical Level
Feb 26,2008
Fatimah Alakeel

22. Data Models
Data Model is a set of concepts for describing the structure of a DB (data, relationships, constraints)
Used for the conceptual and view levels
Categories of data models:
- Object-based conceptual model
- Record-based logical model
- Physical model
Feb 26,2008
Fatimah Alakeel

23. Categories of Data Models
Object-based conceptual model
The structure of the database is flexible
Data constraints specified explicitly
Examples:
Entity Relationship Model (ER)
Object Oriented Models (OO)
Characteristics:
Entities represent things in the real world
Entities are distinct
New kind of entities can be constructed from old kinds
Feb 26,2008
Fatimah Alakeel

24. Categories of Data Models
Record-based logical model
Data viewed as a fixed- format records of various types.
Examples:
Relational model
Network model
Hierarchical model
Feb 26,2008
Fatimah Alakeel

25. Data Models Relational Model Network Model Staff_No LName Salary
Brn_No
Brn_No
Street
Tel_No
Relational
Model
St Name
Olayaa
Malaz
Rawda
St Name
St Name
St Name
St Name
Olayaa
Malaz
Network
Model
St Name
Rawda
St Name
St Name
Feb 26,2008
Fatimah Alakeel

26. Data Models Hierarchical Model Malaz 4780000 Olayaa 4630000
Rawda
St Name
St Name
St Name
St Name
Hierarchical
Model
Feb 26,2008
Fatimah Alakeel

27. Database Systems (DBS)
Virtual data derived from the data base
View 1
View 2
Staff_No FName LName Age Salary
Staff_No LName Bno
Staff_No FName LName DOB Salary Bno
DBS Support of Multiple Views of Data
Feb 26,2008
Fatimah Alakeel

28. Database Systems (DBS)
Sharing of data and multiuser transaction processing
DBMS includes concurrency control software => to ensure that several users trying to update the same data can do that in a controlled manner so the result of the update is correct.
Feb 26,2008
Fatimah Alakeel

29. Actors in the Scene
Database Administrator (DBA): administrates the DB, DBMS & related software
Database Designer: Identify the data & choose the appropriate structure to represent & store the data
Database user: Queries/modifies data
- Naïve users: invoke one of the permanent application programs that have been written previously
- Sophisticated users: form requests in a database query language
Feb 26,2008
Fatimah Alakeel

30. Actors in the Scene
System Analyst: determine the requirements of end users & develop system specifications
Application Programmer: implement system specifications
DBMS designer & Implementers
Tool Developer
Operators & Maintenance Personnel
Feb 26,2008
Fatimah Alakeel

31. DBS Environment User Procedure Requirement DB Designer System Analyst
Communicate
Procedure
User
Requirement
Write
Write
DB Designer
System Analyst
Application
programmer
Design
DBA
Program
Manage
App
Program
DBMS
Use
Naïve End User DB
Use
Sophisticated End User
H/W
Feb 26,2008
Fatimah Alakeel

32. When Not to Use a DBMS
High initial investment in H/W, S/W and training.
Generality provided by DBMS for defining and processing data.
Overhead for providing security, concurrency control, recovery and integrity functions.
Database & applications are simple, well defined, not expected to change.
Real-time requirements can not be met because of overhead.
Multiple-user access to data is not required.
Feb 26,2008
Fatimah Alakeel

33. Chapter’s Summery
Definition of ( Data, Information ,Database, Database application).
Properties of (database, data stored in the database).
DBMS definition, properties and responsibilities.
File based system vs. database system
Database system characteristics.
Data models
Actors in the scene.
When not to use a DBMS.
Feb 26,2008
Fatimah Alakeel