Texas State Technical College
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Modeling the Real WorldModeling the Real World
Its all about perspective.
Texas State Technical College
DISCOVER!
Modeling the World
Computers are used in the everyday Computers are used in the everyday world, thus every computer system must world, thus every computer system must model a real world domain.model a real world domain.
• AccountingAccounting• FinanceFinance• Human ResourcesHuman Resources• Inventory ManagementInventory Management• SalesSales
This applies to databases too.This applies to databases too.
Why model?Why model?
Texas State Technical College
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Modeling the World
The Problem…The Problem…Modeling the system:Modeling the system: Early computer models forced the domain representation Early computer models forced the domain representation to fit a structure that didn’t accurately model the real to fit a structure that didn’t accurately model the real world.world.
The Solution…The Solution…Object Oriented Approaches:Object Oriented Approaches:
Model the computer systems after the real world. Model the computer systems after the real world.
The Evolution of ModelingThe Evolution of Modeling
Texas State Technical College
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Modeling the WorldEarly Design ApproachesEarly Design Approaches
Failings: Failings:
• Lack of data Lack of data encapsulationencapsulation
• All the attributes that described a real world object All the attributes that described a real world object were separate, independent pieces that had to be were separate, independent pieces that had to be tracked. They needed to be packaged together.tracked. They needed to be packaged together.
• Weak ability to define Weak ability to define relationshipsrelationships
• Since there is no tangible object, how do you define Since there is no tangible object, how do you define relationships with other non-tangible objects?relationships with other non-tangible objects?
Texas State Technical College
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Modeling the WorldObject Oriented DesignObject Oriented Design
Key Concept: Key Concept:
• Everything is viewed and created as independent Everything is viewed and created as independent objects.objects.
Implies:Implies:
• Everything is an object, even actions and events.Everything is an object, even actions and events.
• Each object is a package of attributes Each object is a package of attributes (encapsulated)(encapsulated), , components, and defined components, and defined relationshipsrelationships to other types of to other types of objects.objects.
Texas State Technical College
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Modeling the WorldObject Oriented ExampleObject Oriented Example
[[Car Engine SimpleCar Engine Simple] ]
Alternator
attributes:• voltage
• watts
• max torque
Battery
attributes:• voltage total
• voltage charged
Engine
attributes:• max HP
• max Torque
• fuel capacity
• volume
contains
contains
charges
Texas State Technical College
DISCOVER!
Modeling the WorldObject Oriented ExampleObject Oriented Example
[[Car Engine DetailedCar Engine Detailed] ]
Alternator
attributes:• voltage
• watts
• max torque
Battery
attributes:• voltage total
• voltage charged
Engine
attributes:• max HP
• max Torque
• fuel capacity
• volume
contains
contains
Terminal
attributes:• Type: Positive
Terminal
attributes:• Type: Negative
Wire
attributes:• Capacity
•Resistance
Wire
attributes:• Capacity
•Resistance
contains
connected
connected
connected
Terminal
attributes:• Type: Positive
Terminal
attributes:• Type: Negative
contains connected
Texas State Technical College
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Modeling the WorldObject Oriented ExampleObject Oriented Example
[[InventoryInventory]]
Item
attributes:• size
• color
• category
Customer
attributes:• name
• address
Order
attributes:• Item Identifier
• Customer Identifier
• Date
• Quantity
Placed by
For Purchase Of
Texas State Technical College
DISCOVER!
Modeling the WorldObject Oriented ExampleObject Oriented Example
[[Department of Motor Department of Motor VehiclesVehicles]] Vehicle
attributes:• VIN
• Color
• Make
• Year
License Plate
attributes:• Identifier
• Registration #
• Year Issued
Registrant
attributes:• SSN
• Name
• Age
• Address
Ownership by
Identifies
Registration
attributes:• Registrant #
• Vehicle #
• Date Registered
• Date ExpiredO
wne
rshi
p of
Texas State Technical College
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Modeling the WorldObject Oriented AnalysisObject Oriented Analysis
• Most accurate representation of the real world.Most accurate representation of the real world.
• Allows designers to better model the real world.Allows designers to better model the real world.
• Leaves control to the designer, simple models will work Leaves control to the designer, simple models will work but can also be as detailed as needed.but can also be as detailed as needed.
• Flexible enough to be used in the design of any system.Flexible enough to be used in the design of any system.
• Traditionally used primarily for programming languages.Traditionally used primarily for programming languages.• C++C++• JavaJava
• DatabaseDatabase design is best visualized as design is best visualized as Object OrientedObject Oriented..
Texas State Technical College
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Modeling the WorldRelational DatabasesRelational Databases
• Are the most common and frequently used means of Are the most common and frequently used means of information storage and organization.information storage and organization.
• Utilize an object oriented perspective and design.Utilize an object oriented perspective and design.
• Represent Represent objectsobjects through the use of tables. through the use of tables.
• Represent object Represent object attributesattributes through the use of fields. through the use of fields.
• Represent object Represent object relationshipsrelationships through the use of through the use of keys.keys.
Texas State Technical College
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Modeling the WorldIn Summary…In Summary…
• Relational databasesRelational databases are the most commonly used. are the most commonly used.
• They utilize an They utilize an object orientedobject oriented perspective and design. perspective and design.
• Object oriented Object oriented models models allow us to better represent allow us to better represent the real worldthe real world
• Object oriented models Object oriented models capturecapture real world real world objectsobjects, , their their attributesattributes, and their , and their relationshipsrelationships to other to other objects.objects.
• Relational databases Relational databases actualizeactualize the components the components through the use of through the use of tablestables (objects), (objects), fieldsfields (attributes), (attributes), and and keyskeys (relationships). (relationships).
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