Chapter3DataNormalization.ppt


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,DBMS:Designing&BuildingBusinessApplicationsUniversityofManitoba AsperSchoolofBusiness 3500DBMS BobTravicaUpdated2010*of23NormalizationTheprocessofputtingdataintotheformatofrelationaldatabases(anizingdataforrelationaldatabases)Practicallyboilsdowntodefiningtablessothata)problems(anomalies)withinsertion,deletionandmodificationofdataareavoidedb)pleteness,integrity)c)redundancyisreduced*of23RelationalDatabaseTerminologyRelationaldatabase:Acollectionoftables(relations).:Acollectionofcolumns(attributes,properties,fields) describinganentity(class). Tableisalsoacollectionofrows(records)(entityinstances).EmployeeID TaxpayerID LastName FirstName HomePhone Address 12512 888-22-5552 Cartom Abdul (603)323-9893 252SouthStreet 15293 222-55-3737 iaan Roland (804)888-6667 937ParamariboLn 22343 293-87-4343 Johnson John (703)222-9384 234MainStreet 29387 837-36-2933 Stenheim Susan (410)330-9837 (Class):EmployeeTable:Employee*of23RelationalDatabaseTerminology– PrimaryKeyEverytablehasaprimarykey(key)–anattributethatuniquelyidentifieseachrow(.,EmployeeIDonpreviousslide)posite,concatenated):Watchfordatatypes(.,)andnamingrules(arbitrarybutconsistent).OrderItemOrderID ItemID Quantity1 229 21 253 42 229 12 555 4PrimarykeycanbegeneratedautomaticallybyDBMS–-keycolumns.*of23RelationalDatabaseShorthandNotationCustomer(CustomerID,LastName,FirstName,Address,City,State,ZipPostalCode,TelephoneNumber)*TablenameNon-keycolumnsPrimarykeyisunderlinedNote:Telephonenumbercanbeusedasa“backupkey.”*of23OrderManagementApplicationCustomerOrderSalespersonItemOrderItem1*1*11**NormalizedTablesDiagram,SchemaNon-NormalizedClassDiagramCustomerOrderSalespersonItem1*1***OrderItemAssociationclass(ItemOrdered,OrderDetail,etc.)*of23Customer(CustomerID,Name,Address,City,Phone)Salesperson(

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