Conceptual schema design process
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CONCEPTUAL SCHEMA DESIGN PROCESS. Yr 12 IPT. Information Processing and Technology, 2001. Last Lesson. The UoD is the domain of relevant information. An information system is designed through the Conceptual Schema Design Process (CSDP).

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CONCEPTUAL SCHEMA DESIGN PROCESS

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Conceptual schema design process

CONCEPTUAL SCHEMA DESIGN PROCESS

Yr 12

IPT

Information Processing and Technology, 2001


Last lesson

Last Lesson

  • The UoD is the domain of relevant information.

  • An information system is designed through the Conceptual Schema Design Process (CSDP).

  • The first process of the CSDP is to state elementary facts.

  • EF are simple, unambiguous, irreducible and do not contain and, if, or, not, all, some, most.

  • EF contain entities, roles, reference modes and values.

  • The number of entities in an EF describes its arity.

    .


Reference scheme

Reference Scheme

Student (first name)Mary

studies / is studied by

Subject (name)IPT

Entities = Student, Subject

Ref Modes = first name, name

Role = studies / is studied by

Values = Mary, IPT


Arity

Arity

  • The arity of an elementary sentence is the number of entities that associate or play roles

    MaryJogs - unary

    Mary studies English - binary

    Mary received a B for English - ternary


Design cycle

Design Cycle

1.State Elementary Facts

Draw Conceptual Schema Diagram

2.

3.

4.

5.

6.


Step 2 draw conceptual schema diagram

Step 2. Draw Conceptual Schema Diagram

  • The Conceptual Schema Diagrams are a graphical representation of the elementary facts obtained from the first step.

  • Entity types are represented by ellipses:

  • Roles are represented by rectangles:


Data and ef s

Data and EF’s ...

Elementary Facts:

2. Person (name) Gary

lives in / is lived in by

Suburb (suburb) Glenvale.

1. Person (name) Gary

has / refers to

Phone (Phone) 4636 7357.


And a cs diagram

… and a CS Diagram

Phone

(Phone)

Person

(name)

has

1. Person (name) Gary

has / refers to

Phone (Phone) 4636 7357.

lives in

2. Person (name) Gary

lives in / is lived in by

Suburb (suburb) Glenvale.

Suburb

(suburb)


Ternary relationship

Ternary Relationship

1. Student (Student) Megan

studies

Subject (Subject) IPT

gained

Result (Grade) HA


Ternary relationships

Ternary Relationships

  • A ternary relationship is needed when two binary relationships do not convey the information required

  • Ternary relationships are drawn by nesting.


A ternary relationship

A Ternary Relationship

Subject

(subject)

Student

(student)

studies

1. Student (student) Megan

studies

Subject (subject) IPT

gained

Result (grade) HA

gained

Result

(grade)


Ternary or binary

Ternary or Binary?


Summary

Summary

  • Drawing the CS Diagrams is the second step of the CS Design Process.

  • CS Diagrams are a graphical representation of elementary facts.

  • Ternary relationships require nesting.

Entity

(ref mode)

Entity

(ref mode)

plays role


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