Transcription of n Database Modeling representation of the …
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n Database Modeling representation of the …
1DB212 Peter Lo 20041 Database Modeling (Part 1)DB212 Peter Lo 20042 Entity-Relationship ModelnA conceptual data model, which is a representation of the structure of a Database that is independent of the software that will be used to implement the databaseDB212 Peter Lo 20043 Entity-Relationship ModelNameEmployee nameAddressEMPLOYEEDB212 Peter Lo 20044 EntitynAn Entity can be a person, place, object, event or concept in the user environment about which the organization wishes to maintain :uPerson:EMPLOYEE, STUDENT, PATIENTuPlace:STATE, REGION, COUNTRYuObject:MACHINE, BUILDINGuEvent:SALE. REGISTRATIONuConcept: ACCOUNT, COURSEE ntity2DB212 Peter Lo 20045 Entity Type and Entity is a difference between Entity Typeand Entity Type is a collection of entities that share commonproperties or characteristicsuEntity Instance is a single occurrenceof an entity typeDB212 Peter Lo 20046 ExamplesnEntity type:EMPLOYEEnAttributes:uEMPONOuNAMEuAD DRESSuYEARHIREDnInstances:100101 Roy LimMary WongHong KongKowloon19891999DB212 Peter Lo 20047 Attribut
2 DB212 © Peter Lo 2004 5 Entity Type and Entity Instance. nThere is a difference between Entity Typeand Entity Instance. uEntity Type is a collection of entities that share
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