1. Chapter-1- Basic Concepts Reference: Prof. Mona Mursi Lecture notes
Database Design
Chapter-1- Basic Concepts
Reference:
Prof. Mona Mursi Lecture notes
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 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
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3. Database Application: Examples
KSU Library
Saudia Airline Reservations
Car rental DB
A DB for all schools in Riyadh
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4. Database Properties Represents the real world (miniworld)
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)
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5. The Data in the DB are
Shared by multiple Application (users and programs )
Stored less redundantly
Made independent of applications
Organized to provide a foundation for future application.
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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)
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7. DBS Environment DBS Application Programs DBMS Query Process
Data Access
Meta-Data
Database
Database System = Database + DBMS
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8. DBMS Capabilities & Responsibilities
Control redundancy.
Access a large amount of data efficiently.
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 from unauthorized access .
Recover from failures.
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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
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10. Advantages of Database Systems over Paper-Based Systems
Compactness
Speed
Less of hard work
Accurate .
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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
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12. 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
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13. 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
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14. 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.
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15. 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.
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16. 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 Implementers
Physical Level
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17. Characteristics of DB Approach
DBS Support of Multiple Views of Data
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
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18. Characteristics of DB Approach
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.
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19. 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 logical model
- Record-based logical model
- Physical model
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20. Categories of Data Models
Object-based logical model
Examples:
Entity Relationship Model (ER)
Object Oriented Models (OO)
Characteristics:
Data is viewed as sets Entities represent things in the real world
Entities are distinct
New kind of entities can be constructed from old kinds
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21. 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
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22. Example Field STUDENT Name StudentNumber Class Major Record Smith 17 1CS
Brown 8 2 CS
COURSE
CourseName
CourseNumber
CreditHours
Department
Discrete Mathematics
MATH2410 3
MATH
Database
CS3380 4 CS
SECTION
SectionIDentifier
CourseNumber
Semester
Year
Instructor 85
MATH2410
Fall 03
Anderson
135
CS3380
Fall 04
Stone
GRADE_REPORT
StudentNumber
SectionIDentifier
Grade 17 85 A 17
135 B 8
135 A
PREREQUISITE
CourseNumber
PrerequisiteNumber
MATH222
MATH211
CS3380
CS210
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