简介：Aviewinobjectorienteddatabasescorrespondstovirtualschemawithrestructuredgeneralizationanddecompositionhierarchies,Numbersofviewcreationmethodologieshavebeenproposed.Amajordrawbackofexistingmethodologiesisthattheydonotmaintaintheclosureproperty.Thatis,theresultofaquerydoesnothavethesamesemanticsasembodiedintheobjectorienteddatamodel.Teherefore,thispaperpresentsaviewcreationmethodologythatderivesaclassinresponsetoauser'squery,integratesderivedclassinglobalschema(i.e.,considerstheproblemofclassesmovinginclasshierarchy)andselectstherequiredclassesfromglobalschematocreatetheviewforuser'squery.Novelideaofviewcreationincludes:(a)anobjectalgebraforclassderivationandcustomization(wherethederivedclassesintermsofobjectinstancesandprocedure/methodsarestudied),(b)maintenanceofclosureproperty,and(c)classificationalgorithmwhichprovidesmechanismtodealwiththeproblemofaclassmovinginaclasshierarchy.