ENTITYRELATIONSHIP NOTATIONS

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ENTITY-RELATIONSHIP NOTATIONS

• Basic Symbols
• entity
• relationship
• primary key
• attribute
• multi valued attribute
• gerund

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RELATIONSHIP DEGREE

• Unary 1
• Binary 2
• Ternary 3

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RELATIONSHIP CARDINALITY

• Mandatory 1 cardinality
• Many (M) cardinality (1,2,., many)
• Optional 0 or 1 cardinality
• Optional zero-many cardinality(0,1,2,many)

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CLASS-SUBCLASS RELATIONSHIP

• ISA

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EXCLUSIVE RELATIONSHIP

• Exclusive relationship
• U

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Employees - Projects

• A company has a number of employees.
• The attribute of EMPLOYEE include NAME, ADDRESS,
  and BIRTHDATE.
• The company also has several projects. Attributes
  of PROJECT include CODE, DESCRIPTION, and START
  DATE.
• Each employee may be assigned to one or more
  projects, or may not be assigned to a project. A
  project must have at least one employee assigned,
  and may have several employees assigned.

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M 164 2.a. Employee - Project
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COURSES

• A university has a large number of courses in its
  catalog.
• Attributes include NO., NAME, and UNITS.
• Each course may have one or more other courses as
  prerequisites.

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M 164 2.b. COURSES
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Chemists - Projects Equipment

• A laboratory has several chemists who work on
  various projects and who may use certain kinds of
  equipment on each project. Attributes of CHEMIST
  include NAME and Phone No. Attributes of PROJECT
  include PROJECT ID and START DATE. Attributes of
  EQUIPMENT include NUMBER and COST.

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M 164 2.c. Chemist -Projects - Equipment
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COURSE - SECTIONS

• A college course may have one or more scheduled
  sections, or may not have a scheduled section.
• Attributes of COURSE include COURSE ID, SECTION
  NO., and INSTRUCTOR.

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M 164 2.d. Course-Section
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VEHICLES

• Draw an E-R diagram to represent the following
  entity types and the natural relationships among
  them
• VEHICLE, LAND VEHICLE, WATER VEHICLE, OCEAN
  VESSEL, RIVER RAFT, HELICOPTER, RAIL VEHICLE,
  BICYCLE, AIRPLANE, ROAD VEHICLE, CAR.

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M 164 3. VEHICLE
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GRADE REPORT

• NAME, ID, CAMPUS ADDRESS, MAJOR,
• COURSE ID, COURSE TITLE
• INSTRUCTOR NAME, INSTRUCTOR LOCATION
• GRADE

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M 164 4.a.
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HOMEWORK 1

• DUE MONDAY SEPTEMBER 21, 1998
• Modern Database Management 4th edition
• Page 165
• Problem 5
• Problem 6
• Problem 10
• Problem 12

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ACCESS - TUTORIAL

• The class will meet in AH 300
• next Wednesday September 16, 1998
• 3 PM
• to provide you with a hands-on
• ACCESS TUTORIAL
• please take advantage of this resource