Chapter 05 - Chapter 5 Understanding Entity Relationship...

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Unformatted text preview: Chapter 5 Understanding Entity Relationship Diagrams 5-2 Outline Notation basics Understanding relationships Generalization hierarchies Business rule representation Diagram rules Alternative notations 5-3 Basic Symbols Entity Type symbol Relationship symbol Primary Key Attributes Relationship name Entity Type name CourseNo CrsDesc CrsUnits Course OfferNo OffLocation OffTime Offering Has 5-4 Cardinalities Course Offering Course1 Offering1 Course2 Course3 Offering2 Offering3 Offering4 5-5 Cardinality Notation 5-6 Classification of Cardinalities Minimum cardinality based Mandatory: existence dependent Optional Maximum cardinality based Functional 1-M M-N 1-1 5-7 Summary of Cardinalities 5-8 More Relationship Examples FacSSN FacSalary FacRank FacHireDate Faculty OfferNo OffLocation OffTime Offering TeamTeaches OfficeNo OffPhone OffType Office WorksIn 5-9 Comparison to Access Notation Course Courseno CrsDesc CrsUnits 1 8 Offering OfferNo CourseNo OffLocation OffTime ... Access Relationship Diagram 5-10 Understanding Relationships Identification dependency M-N relationships with attributes Self identifying relationships M-way relationships Equivalence between M-N and 1-M relationships 5-11 Identification Dependency BldgID BldgName BldgLocation Building RoomNo RoomCapacity Room Contains Identification Dependency Symbols: Solid relationship line for identifying relationships Diagonal lines in the corners denote weak entities. 5-12 M-N Relationships with Attributes 5-13 M-N Relationships with Attributes (II) 5-14 Instance Diagrams for Self- Referencing Relationships Faculty1 Faculty2 Faculty3 Faculty4 Faculty5 IS300 IS320 IS480 IS460 IS461 (a) Supervises (b) PreReqTo 5-15 ERD Notation for Self-Referencing Relationships...
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Chapter 05 - Chapter 5 Understanding Entity Relationship...

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