GETTINGTFAMILIARTWITHTTERMS

 

1.TERTMODELT:TTheTentityTrelationshipTdataTmodelTonTaTperceptionTofTaTrealTworldTthatTconsistsTofTaTcollectionTofTbasicTobjectsTcalledTentitiesTandTofTrelationshipsTamongTthem.TThisTrepresentsTtheTlogicalTstructureTofTanTdatabase.

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2.TENTITIEST:TAnTentityTisTaTthingTinTtheTrealTworldTthatTisTdistinguishableTfromTallTotherTobjects.Can be person, place, event, object, concept in the real worldCan be physical object or abstractionEx: “John”, “CSE305”

3.TATTRIBUTEST:TAnTentityTisTrepresentedTbyTaTsTetTofTattributes.TTheseTareTdescriptiveTpropertiesTpossessedTbyTeachTmemberTofTtheTentityTset. 

4.TRELATIONSHIPTSETST:TATrelationshipTsetTisTaTsetTofTrelationshipsTofTtheTsameTtype.

5.TCONSTRAINTST:TAnTE-RTenterpriseTschemaTmayTdefineTcertainTconstraintsTtoTwhichTtheTdatabaseTmustTconform.

6.TENTITYTSETST:TATsuperkeyTisTaTsetTofToneTorTmoreTattributesTthatTtakenTcollectively,allowTusTtoTidentifyTuniquelyTanTentityTinTanTentityTset.

7.TN-ARYTRELATIONSHIPST:TGenerallyTtheTrelationshipsTareTbinary,TsometimesTtheTdatabaseThasTmoreTthanToneTentity,TsoTtheyThaveTtertiaryTorTn-aryTrelationships.TThisTparticularTmodelTisTaTtertiaryTrelationshipT(threeTentityTsets).

8.TMAPPINGTCARDINALITIEST:

?TONE-TO-ONET:TEveryTentityTinTeachTofTtheTtwoTentityTsetTareTatTmostTrelatedTtoToneTentityTeach.

?TONE-TO-MANY:TAnTentityTinTcustomerTisTassociatedTwithTaTnumberTofTentitiesTinTorder.ButTAnyTentityTinTorderTcanThaveTatTmostToneTentityTinTcustomer.

?TMANY-TO-ONE:TAnTentityTinTsetTATisTassociatedTwithTatTmostToneTentityTinTB.TButTAnyTentityTinTBTcanTbeTassociatedTwithTaTnumberTofTentitiesTinTA.

?TMANY-TO-MANY:TAnTentityTinTproductTcanTbeTassociatedTwithTaTnumberTofTentitiesTinTorderTandTviceTversaTisTalsoTtrue.

9.TANTE-RTDIAGRAMTCOMPOSESTOFTTHESETMAJORTCOMPONENTST:T?TRECTANGLEST-TEntityTsetsT(TCUSTOMER,TPRODUCT,TORDER)

?TELLIPSEST-AttributesT(C-ID,FIRSTNAME,LASTNAME,QUANTITY,TSTREET,STATE,ETC..TFromTtheTexample)

?TDIAMONDS-TRelationshipTsetsT(customer-PLACES-order.Torder-LISTS-products)T?TLINES-TlinkingTentityTsets,TattributesTandTrelationshipTsets.