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ERD Exercise #2 CIS458 Organizational Database Management Identify all the entities. Identify all the relationships. Identify cardinality and multiplicities (min max). Creating an ERD from the Investigated Facts (1..*) (0..1) (0..*) (1..1) Simple ERD 1

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erd exercise 2

ERD Exercise #2

CIS458

Organizational Database Management

creating an erd from the investigated facts
Identify all the entities.

Identify all the relationships.

Identify cardinality and multiplicities (min max).

Creating an ERD from the Investigated Facts

(1..*) (0..1) (0..*) (1..1)

simple erd 1
Simple ERD 1
  • A painter can paint many paintings; each paining is painted by one painter. A gallery can have many paintings. A painting can be exhibited by a gallery.

Paint ►

(0..*)

Displayed

(1..1)

Painter

(1,1)

(0..*)

Painting

Gallery

simple erd 2
Simple ERD 2
  • An employee can learn many skills; each skill can be learned by many employees.
  • Expert Level? (L1.. L5)

Learn ►

(0..*)

(0..*)

Employee

Skills

Expert Level

simple erd 3
Simple ERD 3
  • An employee manages one store; each store is managed by one employee

Employee

Store

Manages ►

(0..1)

(1..1)

Employee

Store

simple erd 4
Simple ERD 4
  • A College example
  • Students in a typical college or university will discover that each course can have many sections or no section, by each section refers to only one course.
  • For example, an Accounting II course might have two sections: one offered on Monday, Wednesday, and Friday from 10:00 a.m. to 10:50 a.m., and one offered on Thursday from 6:00 p.m. to 8:40 p.m.
slide7

Has ►

(1..1)

(0..*)

Course

Section

simple erd 5
Simple ERD 5
  • Each student can take many classes (or no class at all) and each class can contain many students.
  • Add Grade

Take ►

(1..*)

(0..*)

Student

Classes

Grade

combining erds
Combining ERDs
  • A class can be identified with course and section.

Has ►

(1..1)

(0..*)

Course

Section

Take ►

(1..*)

(0..*)

Student

Section

slide10

Has ►

(1..1)

(0..*)

Course

Section

(0..*)

Take▼

(1..*)

Student

adding additional conditions
Adding Additional Conditions
  • Adding prerequisite, enroll grade

Has ►

(1..1)

(0..*)

Course

Section

(0..*)

(0..*)

(0..*)

Take ▼

Grade

◄Prerequisite

(1..*)

Student