Chapter 3 The Enhanced E-R Model

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Chapter 3 The Enhanced E-R Model
Jason C. H. Chen, Ph.D. Professor of MIS School
of Business Administration Gonzaga
University Spokane, WA 99258 chen_at_jepson.gonzaga.e
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3-c (p.144)
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3-d (p.144)
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Please note that the problem does not explicitly
state that Skill is a multivalued attribute.
Given the fact that examples in the text have
skill as a multivalued attribute, we have made
this assumption here also.
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Note Again, we have assumed that Skill is a
multivalued attribute.. Standard EER Notation
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Subtypes inside Supertypes Notation
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Subtypes inside Supertypes Notation
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Subtypes within Supertypes Notation
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Subtypes within Supertypes Notation
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Notes for EERD 1) Member Type values are Golf
or Non-Golf. 2) Social and Tennis members are
considered Non-Golf members. A Social member has
a Golf Rounds Limit of 2 and Tennis Courts? N.
A Tennis member has a Golf Rounds Limit of 4 and
Tennis Courts?Y. A Golf member has a Golf
Rounds Limit of 999 and Tennis Courts?Y. 3)
Golf members visits are tracked only if they
bring a guest. 4) If a Guest becomes a Member,
then Guest records are archived out of the
database. 5) Member Date tracks the membership
date of the Member.
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Notes 1) A PERSON, in his/her EMPLOYMENT, may
hold multiple POSITIONs or not yet have an
assigned POSITION (this is shown with the 0M
cardinality near POSITION from EMPLOYMENT). 2) A
POSITION might initially be unfilled, or over
time, may be filled with multiple EMPLOYMENT
instances of PERSONs (this is shown by the 0M
cardinality near EMPLOYMENT from POSITION).
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