3902 Chapter 1

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DATABASE By Mr. Abdalla A. Shaame
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Outline

• What is a database?
• The main characters of a database system
• The basic database design method
• The entity-relationship data model for
  application modeling

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• Types of databases
• traditional
• multimedia - pictures, video, sound
• Scientific database
• - GIS maps, weather, satellite images
• - biological database DNA sequence analysis
• warehouse, OLAP - analysis, decision making
• real-time, active databases - industrial
  processes
• deductive databases - combination of inference
  and
• databases

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• Database
• collection of related data
• represents some aspect of the real world
• built with a specific purpose in mind
• could be anywhere - notebook, spreadsheet,
  Access, Oracle, could be manual / could be
  computerized
• Data
• known and recordable facts
• name, phone number, address, grade, ...

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Database Components

• A database system is composed of four components
• Data
• Hardware
• Software
• Users

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Database System
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• Database Management System (DBMS)
• collection of software facilitating the
  definition,
• construction and manipulation of databases

• Definition
• record structure
• data elements
• names
• data types
• constraints
• etc

• Manipulation
• querying
• updating

• Construction
• create database
• files
• populate the
• database with
• records

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• Database Management System (DBMS)
• collection of software facilitating the
  definition, construction and manipulation of
  databases

DBMS
Meta data
Request manager
Storage manager
Stored database
Users/actors
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• Characteristics of the Database approach
• single repository of data
• sharable by multiple users
• concurrency control
• transaction control
• self-describing - system catalogue contains meta
  data
• program-data independence
• some changes to the database are transparent to
• programs/users
• multiple views of data - to support individual
  needs of programs/users

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• Database Actors
• Database Administrator (DBA) - authorizing
  access to the database - coordinating and
  monitoring its use - aquiring software and
  hardware as needed - solving problems such as
  breach of security or poor system performance
• Database Designers/Modelers - identifying the
  data to be stored - choosing appropriate data
  structure
• End-users - access to the database
  querying, updating, generating reports
• Software Engineers - developing application
  programs

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• Advantages of the Database approach
• (capabilities we would look for in a DBMS)
• controlled redundancy
• database design integrates different user data
  needs
• performance tuning may lead to replicated data
• Sharing of the data
• controlled/authorized access to data
• Ensure integrity of the data
• backup and recovery

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• Implications of the Database approach
• standards enforcement
• DBA can enforce standard naming conventions, etc
• reduced application development time
• adding new functionality to an existing database
  is
• easy
• flexibility
• adding new data and making some types of changes
  is easy
• up-to-date information - due to sharable
  characteristic
• economies of scale - due to sharable resources
  the whole
• organization can make one investment

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• When not to use a DBMS
• overhead costs are too great
• high initial investment
• data and applications are simple, well-defined,
  not expected to change
• stringent real-time constraints
• multi-user environment not needed

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• Database design
• lets jump ahead to see this

Course
1
Student
Delivery
N
M
Grades
Section
N
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• Database design
• lets jump ahead to see this

Course
StNo
1
Student
Class
Delivery
Major
Name
N
M
Grades
Section
N
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• Database design
• lets jump ahead to see this

CNo
CrHrs
Dept
Course
CName
StNo
1
Student
Class
Delivery
Major
Name
N
M
Grades
Section
N
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• Database design
• lets jump ahead to see this

CNo
CrHrs
Dept
Course
CName
StNo
1
Student
Class
Delivery
Major
Name
N
M
Semester
Grades
Section
N
Year
SId
Instructor
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• Database design
• lets jump ahead to see this

CNo
CrHrs
Dept
Course
CName
StNo
1
Student
Class
Delivery
Major
Name
N
M
Semester
Grades
Section
N
Year
grade
SId
Instructor
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With attributes, etc
name
number
location
1
works for
lname
fname
minit
department
N
salary
address
name
sex
number of employees
1
startdate
1
controls
ssn
manages
employee
1
bdate
1
N
N
hours
supervisor
N
degree
supervisee
M
works on
supervision
1
project
dependents of
name
number
location
N
dependent
relationship
birthdate
name
sex
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• ER-to-Relational mapping
• 1. Create a relation for each strong entity type
• 2. Create a relation for each weak entity type
• include primary key of owner (an FK - foreign
  key)
• owners PK partial key becomes PK
• 3. For each binary 11 relationship choose an
  entity and include the others PK in it as an FK.
  Include any attributes of the relationship
• 4. For each binary 1n relationship, choose the
  n-side entity and include an FK of the other
  entity. Include any attributes of the relationship

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• 5. For each binary MN relationship, create a
  relation for the relationship
• include PKs of both participating entities and
  any attributes of the relationship
• PK is the concatenation of the participating
  entity PKs
• 6. For each multivalued attribute create a new
  relation
• include the PK attributes of the entity type
• PK is the PK of the entity type and the
  multivalued attribute
• 7. For each n-ary relationship, create a relation
  for the relationship
• include PKs of all participating entities and any
  attributes of the relationship
• PK may be the concatenation of the participating
  entity PKs