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# CONCEPTUAL SCHEMA DESIGN PROCESS - PowerPoint PPT Presentation

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

Yr 12

IPT

Information Processing and Technology, 2001

• 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.

.

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

• 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

1. State Elementary Facts

Draw Conceptual Schema Diagram

2.

3.

4.

5.

6.

• 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:

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.

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)

1. Student (Student) Megan

studies

Subject (Subject) IPT

gained

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

• Ternary relationships are drawn by nesting.

Subject

(subject)

Student

(student)

studies

1. Student (student) Megan

studies

Subject (subject) IPT

gained

gained

Result

• 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