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COMM 335 (2)
Lecture

Class 4 - Introduction to Database.pdf

2 Pages
147 Views

Department
Commerce
Course Code
COMM 335
Professor
Y.M.Cheung

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Description
Class 4Tuesday May 15 20121002 AMCommon Errors in designing tablesNon unique primary keysusing firstlast name as PKForeign Key name does not correspond to the actual data A PK called CustID is called CustName in another tableDuplicate data across two tables FirstLast name of a customer in two tablesNote While it is possible to have a database with 1 table that fulfills all the user requirements lots of duplication will occur AnomaliesDesigning Database with ERDEntity Relationship Diagram is a technique to model real objects in a database Database users builder designer refer an object with different terms such asExampleDesignerBuilderUserCustomerEntityTableListVincentEntity OccurrenceRecordInfoFor the purpose of this course we will useCrows Feet notationOneOZeroCrows FeetManyAn artist could have 0 to many songs a song can only have one artistEntity Person object event concept the user environment about which organization wishes to maintain da
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