AppendixfCfThefUniversityfLab:
ConceptualfDesignfVerification,fLogicalfDesign,fandfImplementation
Appendix C
The University Lab: Conceptual Design, Verification,
Logical Design, and Implementation
DiscussionfFocus
Howfisfafdatabasefdesignfverified,fandfwhyfisfsuchfverificationfnecessary?
Usefourfdetailedfanswerftofquestionf1ftoffocusfclassfdiscussionfonfdatabasefdesignfverification.fStressfthatf
thefverificationfprocessfusesfthefinitialfERfmodelfasfafcommunicationftool.
Thefdesignerfmayfbeginfthefverificationfprocessfbyfdescribingftheforganization'sfoperationsftofitsfendfuser
s,fbasingfthefdetailedfdescriptionfonfthefinitialfERfmodel.fNext,fexplainfhowfthefoperationsfwillfbefsupporte
dfbyfthefdatabasefdesign.fStressfthatfthefdesignfmustfsupportfthefend-
userfapplicationfviews,foutputs,fandfinputs.fPointsftofbefaddressedfincludefsuchfquestionsfas:
Isfthefdescriptionfaccurate?fIffnot,fwhatfaspectsfoffthefdescriptionfmustfbefcorrected?
Doesf thef modelf supportf thef end-userf requirements?f Iff not,f whatf aspectsf off thef end-
userfrequirementsfhavefnotfbeenfaddressedforfhavefbeenfaddressedfinadequately?
Keepf infmindf thatf evenf af modelf thatf perfectlyf addressesf allf initiallyf determinedfendf userf requirementsfisfl
ikelyftofneedfadjustmentsfasfthosefendfusersfbeginftofunderstandftheframificationsfoffthefdatabasefdesign'
sfcapabilities.fInfmanyfcases,fthefendfusersfmayflearnfwhatftheforganization'sfprocessesfandfproceduresfac
tuallyfare,fthusfleadingftofnewfrequirementsfandfthefperceptionfoffnewfopportunities.fThefdatabasefdesign
erfmustfkeepfsuchflikelyfdevelopmentsfinfmind,fespeciallyfiff(s)hefworksfasfafdatabasefdesignfconsultant.f(
Anticipationfoffsuchfdevelopmentsfmustfbeffactoredfintofthefcontractfnegotiationsfforfconsultingffees.)
Discussfthefrolefoffthefsystemfmodules.
1
, AppendixfCfThefUniversityfLab:
ConceptualfDesignfVerification,fLogicalfDesign,fandfImplementation
Thef usef off systemf modulesf canf hardlyf bef overemphasizedf inf af databasef designf environment.f Stressfth
esefmodulefcharacteristicsfandffeatures:
Modulesfrepresentfsubsetsfoffthefdatabasefmodel:fSmallerf"pieces"farefmorefeasilyfundersto
od.
Modulesfarefself-
containedfandfaccomplishfafspecificfsystemffunction;fiffsuchfafsystemffunctionfmustfbefmod
ified,fotherffunctionsfremainfunaffected.
Modulesffitfintofafmodularfdatabasefdesign,fwhichfisfmorefeasilyfmodifiedfandfadaptedftofne
wfcircumstances.fBecausefmodificationfeffortsfareffocusedfonfafdatabasefsubset,fproductivit
yfoffbothfdesignersfandfapplicationfdevelopersfisflikelyftofbefenhanced.
Modulefinterfacesfmustfbefclearfiffthefmodulesfarefexpectedftofworkfwellfwithinfthefoverallfsystem.
2
, AppendixfCfThefUniversityfLab:
ConceptualfDesignfVerification,fLogicalfDesign,fandfImplementation
AnswersftofReviewfQuestions
1. Whyfmustfafconceptualfmodelfbefverified?fWhatfstepsfarefinvolvedfinfthefverificationfprocess?
Thefverificationfoffafconceptualfmodelfisfcrucialftofafsuccessfulfdatabasefdesign.fThefverificationfproce
ssfallowsfthefdesignerftofcheckfthefaccuracyfoffthefdatabasefdesignfby:
Re-examiningfdatafandfdataftransformations.
Enablingf thef designerf tof evaluatef thef designf efficiencyf relativef tof thef endf user'sf andfsy
stem'sfdesignfgoals.
Keepfinfmindfthat,ftofaflargefextent,fthefbestfdesignfisfthefonefthatfservesfthef end-
userfrequirementsfbest.fForfexample,fafdesignfthatfworksfwellfforfafmanufacturingffirmfmayfnotffitfthef
needsfoffafmarketingfresearchffirm,fandfvicefversa.
Thefverificationfprocessfhelpsfthefdesignerftofavoidfimplementationfproblemsflaterfby:
Validatingfthefmodel'sfentities.f(Rememberfthefminimalfdatafrule.)
Confirmingfentityfrelationshipsfandfeliminatingfduplicate,funnecessary,forfimproperlyfd
efinedfrelationships.
Eliminatingfdatafredundancies.
Improvingfthefmodel'sfsemanticfprecisionftofbetterfrepresentfreal-worldfoperations.
Confirmingfthatfallfuserfrequirementsf(processing,fperformance,forfsecurity)farefmet.
Verificationfisfafcontinuousfactivityfinfanyfdatabasefdesign.fThefdatabasefdesignfprocessfisfevolutionar
yfinfnature:fItfrequiresfthefcontinuousfevaluationfoffthefdevelopingfmodelfbyfexaminingfthefeffectfoffa
ddingfnewfentitiesfandfbyfconfirmingfthatfanyfdesignfchangesfenhancefthefmodel'sfaccuracy.
Thefverificationfprocessfrequiresftheffollowingfsteps:
1. Identifyfthefdatabase'sfcentralfentity.
Thef centralf entityf isf thef mostf importantf entityf inf ourf database,f andf mostf off thef otherfen
titiesfdependfonfit.
3
, AppendixfCfThefUniversityfLab:
ConceptualfDesignfVerification,fLogicalfDesign,fandfImplementation
2. Identifyfandfdefinefeachfmodulefandfitsfcomponents.
Thef designerf dividesf thef databasef modelf intof smallerf setsf thatf reflectf thef dataf needsf offpa
rticularfsystemsfmodulesfsuchfasfinventory,forders,fpayroll,fetc.
3. Identifyfandfdefinefeachfoffthefmodule'sfprocesses.
Specifically,f thisf stepf requiresf thef identificationf andf definitionf off thef databasef transactions
thatfrepresentfthefmodule'sfreal-worldfoperations.
4
ConceptualfDesignfVerification,fLogicalfDesign,fandfImplementation
Appendix C
The University Lab: Conceptual Design, Verification,
Logical Design, and Implementation
DiscussionfFocus
Howfisfafdatabasefdesignfverified,fandfwhyfisfsuchfverificationfnecessary?
Usefourfdetailedfanswerftofquestionf1ftoffocusfclassfdiscussionfonfdatabasefdesignfverification.fStressfthatf
thefverificationfprocessfusesfthefinitialfERfmodelfasfafcommunicationftool.
Thefdesignerfmayfbeginfthefverificationfprocessfbyfdescribingftheforganization'sfoperationsftofitsfendfuser
s,fbasingfthefdetailedfdescriptionfonfthefinitialfERfmodel.fNext,fexplainfhowfthefoperationsfwillfbefsupporte
dfbyfthefdatabasefdesign.fStressfthatfthefdesignfmustfsupportfthefend-
userfapplicationfviews,foutputs,fandfinputs.fPointsftofbefaddressedfincludefsuchfquestionsfas:
Isfthefdescriptionfaccurate?fIffnot,fwhatfaspectsfoffthefdescriptionfmustfbefcorrected?
Doesf thef modelf supportf thef end-userf requirements?f Iff not,f whatf aspectsf off thef end-
userfrequirementsfhavefnotfbeenfaddressedforfhavefbeenfaddressedfinadequately?
Keepf infmindf thatf evenf af modelf thatf perfectlyf addressesf allf initiallyf determinedfendf userf requirementsfisfl
ikelyftofneedfadjustmentsfasfthosefendfusersfbeginftofunderstandftheframificationsfoffthefdatabasefdesign'
sfcapabilities.fInfmanyfcases,fthefendfusersfmayflearnfwhatftheforganization'sfprocessesfandfproceduresfac
tuallyfare,fthusfleadingftofnewfrequirementsfandfthefperceptionfoffnewfopportunities.fThefdatabasefdesign
erfmustfkeepfsuchflikelyfdevelopmentsfinfmind,fespeciallyfiff(s)hefworksfasfafdatabasefdesignfconsultant.f(
Anticipationfoffsuchfdevelopmentsfmustfbeffactoredfintofthefcontractfnegotiationsfforfconsultingffees.)
Discussfthefrolefoffthefsystemfmodules.
1
, AppendixfCfThefUniversityfLab:
ConceptualfDesignfVerification,fLogicalfDesign,fandfImplementation
Thef usef off systemf modulesf canf hardlyf bef overemphasizedf inf af databasef designf environment.f Stressfth
esefmodulefcharacteristicsfandffeatures:
Modulesfrepresentfsubsetsfoffthefdatabasefmodel:fSmallerf"pieces"farefmorefeasilyfundersto
od.
Modulesfarefself-
containedfandfaccomplishfafspecificfsystemffunction;fiffsuchfafsystemffunctionfmustfbefmod
ified,fotherffunctionsfremainfunaffected.
Modulesffitfintofafmodularfdatabasefdesign,fwhichfisfmorefeasilyfmodifiedfandfadaptedftofne
wfcircumstances.fBecausefmodificationfeffortsfareffocusedfonfafdatabasefsubset,fproductivit
yfoffbothfdesignersfandfapplicationfdevelopersfisflikelyftofbefenhanced.
Modulefinterfacesfmustfbefclearfiffthefmodulesfarefexpectedftofworkfwellfwithinfthefoverallfsystem.
2
, AppendixfCfThefUniversityfLab:
ConceptualfDesignfVerification,fLogicalfDesign,fandfImplementation
AnswersftofReviewfQuestions
1. Whyfmustfafconceptualfmodelfbefverified?fWhatfstepsfarefinvolvedfinfthefverificationfprocess?
Thefverificationfoffafconceptualfmodelfisfcrucialftofafsuccessfulfdatabasefdesign.fThefverificationfproce
ssfallowsfthefdesignerftofcheckfthefaccuracyfoffthefdatabasefdesignfby:
Re-examiningfdatafandfdataftransformations.
Enablingf thef designerf tof evaluatef thef designf efficiencyf relativef tof thef endf user'sf andfsy
stem'sfdesignfgoals.
Keepfinfmindfthat,ftofaflargefextent,fthefbestfdesignfisfthefonefthatfservesfthef end-
userfrequirementsfbest.fForfexample,fafdesignfthatfworksfwellfforfafmanufacturingffirmfmayfnotffitfthef
needsfoffafmarketingfresearchffirm,fandfvicefversa.
Thefverificationfprocessfhelpsfthefdesignerftofavoidfimplementationfproblemsflaterfby:
Validatingfthefmodel'sfentities.f(Rememberfthefminimalfdatafrule.)
Confirmingfentityfrelationshipsfandfeliminatingfduplicate,funnecessary,forfimproperlyfd
efinedfrelationships.
Eliminatingfdatafredundancies.
Improvingfthefmodel'sfsemanticfprecisionftofbetterfrepresentfreal-worldfoperations.
Confirmingfthatfallfuserfrequirementsf(processing,fperformance,forfsecurity)farefmet.
Verificationfisfafcontinuousfactivityfinfanyfdatabasefdesign.fThefdatabasefdesignfprocessfisfevolutionar
yfinfnature:fItfrequiresfthefcontinuousfevaluationfoffthefdevelopingfmodelfbyfexaminingfthefeffectfoffa
ddingfnewfentitiesfandfbyfconfirmingfthatfanyfdesignfchangesfenhancefthefmodel'sfaccuracy.
Thefverificationfprocessfrequiresftheffollowingfsteps:
1. Identifyfthefdatabase'sfcentralfentity.
Thef centralf entityf isf thef mostf importantf entityf inf ourf database,f andf mostf off thef otherfen
titiesfdependfonfit.
3
, AppendixfCfThefUniversityfLab:
ConceptualfDesignfVerification,fLogicalfDesign,fandfImplementation
2. Identifyfandfdefinefeachfmodulefandfitsfcomponents.
Thef designerf dividesf thef databasef modelf intof smallerf setsf thatf reflectf thef dataf needsf offpa
rticularfsystemsfmodulesfsuchfasfinventory,forders,fpayroll,fetc.
3. Identifyfandfdefinefeachfoffthefmodule'sfprocesses.
Specifically,f thisf stepf requiresf thef identificationf andf definitionf off thef databasef transactions
thatfrepresentfthefmodule'sfreal-worldfoperations.
4
