Transcript Elektronik Yayıncılık ve Bilimsel İletişim: Teknoloji

“DOK 322 DBMS”
Database Design
Hacettepe University
Department of Information Management
DOK 322: Database Management
Systems
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“DOK 322 DBMS”
Last Time
 File
Management Systems vs. DBMSs
 Advantages and Disadvatages of DBMS
 Components of DBMS
 MS Access 2000 (Lab)
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“DOK 322 DBMS”
DBMS Benefits
Minimal Data Redundancy
Consistency of Data
Integration of Data
Sharing of Data
Ease of Application Development
Uniform Security, Privacy, and Integrity
Controls
 Data Accessibility and Responsiveness
 Data Independence
 Reduced Program Maintenance
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“DOK 322 DBMS”
Database Environment
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CASE
Tools
User
Interface
Repository
DBMS
Application
Programs
Database
“DOK 322 DBMS”
Database Components
DBMS
===============
Design tools
Database
Database contains:
User’s Data
Metadata
Indexes
Application Metadata
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Table Creation
Form Creation
Query Creation
Report Creation
Procedural
language
compiler (4GL)
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Run time
Form processor
Query processor
Report Writer
Language Run time
Application
Programs
User
Interface
Applications
Kroenke, Database
Processing
“DOK 322 DBMS”
Terms and Concepts
 Database:
– A self-describing collection of integrated
records (Kroenke).
– A collection of similar records with
relationships between the records.
(Rowley)
– A collection of stored operational data used
by the application systems of some
particular enterprise. (C.J. Date)
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“DOK 322 DBMS”
Terms and Concepts

Enterprise
– Organization

Entity
– Person, Place, Thing, Event, Concept...
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Attributes
– Data elements (facts) about some entity
– Also sometimes called fields or items or domains

Data values
– instances of a particular attribute for a particular
entity
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“DOK 322 DBMS”
Terms and Concepts
 Key
– an attribute or set of attributes used to
identify or locate records in a file
 Primary
Key
– an attribute or set of attributes that
uniquely identifies each record in a file
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“DOK 322 DBMS”
Terms and Concepts
 Models
– (1) Levels or views of the Database
 Conceptual,
logical, physical
– (2) DBMS types
 Relational,
Hierarchic, Network, ObjectOriented, Object-Relational
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“DOK 322 DBMS”
Models (1)
Application 1
External
Model
Application 2
Application 3
Application 4
External
Model
External
Model
External
Model
Application 1
Conceptual
requirements
Application 2
Conceptual
requirements
Application 3
Conceptual
requirements
Application 4
Conceptual
requirements
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Conceptual
Model
Logical
Model
Internal
Model
“DOK 322 DBMS”
Database System Life Cycle
Physical
Creation
2
Conversion
3
Design
1
Growth,
Change, &
Maintenance
6
Integration
4
Operations
5
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“DOK 322 DBMS”
Another View of the Life Cycle
Integration
4
Operations
5
Design
Physical
1
Creation Conversion Growth,
2
Change
3
6
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“DOK 322 DBMS”
Database Models
 Models(2):
DBMS types
– Hierarchical
– Network
– Relational
– Object-Oriented
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“DOK 322 DBMS”
Database Data Models
 Hierarchical
Model
– Similar to data structures in programming
languages.
Books
(id, title)
Authors
(first, last)
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Publisher
Subjects
“DOK 322 DBMS”
Database Data Models
 Network
Model
– Provides for single entries of data and
navigational “links” through chains of data.
Authors
Subjects
Books
Publishers
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“DOK 322 DBMS”
Database Data Models
 Relational
Model
– Provides a conceptually simple model for
data as relations (typically considered
“tables”) with all data visible.
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Title
pubid
Introductio
The history
New stuff ab
Another title
And yet more
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pubname
Harper
Addison
Oxford
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Author name
Smith
Wynar
Jones
Duncan
Applegate
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“DOK 322 DBMS”
Database Data Models
 Object
Oriented Data Model
– Encapsulates data and operations as
“Objects”
Books
(id, title)
Authors
(first, last)
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Publisher
Subjects
“DOK 322 DBMS”
Database Design Process
Application 1
External
Model
Application 2
Application 3
Application 4
External
Model
External
Model
External
Model
Application 1
Conceptual
requirements
Application 2
Conceptual
requirements
Application 3
Conceptual
requirements
Application 4
Conceptual
requirements
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Conceptual
Model
Logical
Model
Internal
Model
“DOK 322 DBMS”
Database Design Process

Conceptual Requirements
– Systems Analysis Process
Examine all of the information sources used in existing
applications
 Identify the characteristics of each data element

–
–
–
–
numeric
text
date/time
etc.
Examine the tasks carried out using the information
 Examine results or reports created using the information

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“DOK 322 DBMS”
Database Design Process

Conceptual Model
– Merge the collective needs of all applications
– Determine what Entities are being used
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Some object about which information is to maintained
– What are the Attributes of those entities?
Properties or characteristics of the entity
 What attributes uniquely identify the entity
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– What are the Relationships between entities
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How the entities interact with each other?
“DOK 322 DBMS”
Database Design Process
 Logical
Model
– How is each entity and relationship
represented in the Data Model of the
DBMS
 Hierarchic?
 Network?
 Relational?
 Object-Oriented?
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“DOK 322 DBMS”
Database Design Process
 Internal
Model
– Choices of index file structure
– Choices of data storage formats
– Choices of disk layout
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“DOK 322 DBMS”
Database Design Process
 External
Model
– User views of the integrated database
– Making the old (or updated) applications
work with the new database design
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Developing a Conceptual Model
Overall view of the database that integrates
all the needed information discovered during
the requirements analysis.
 Elements of the Conceptual Model are
represented by diagrams, Entity-Relationship
or ER Diagrams, that show the meanings and
relationships of those elements independent
of any particular database systems or
implementation details.

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