Appendix C The University Lab:
Conceptual Design Verification, Logical Design, and Implementation
Appendix C
The University Lab: Conceptual Design,
Verification, Logical Design, and
Implementation
Discussion Focus
How is a database design verified, and why is such verification necessary?
Use our detailed answer to question 1 to focus class discussion on database design verification. Stress
that the verification process uses the initial ER model as a communication tool.
The designer may begin the verification process by describing the organization's operations to its end
users, basing the detailed description on the initial ER model. Next, explain how the operations will be
supported by the database design. Stress that the design must support the end-user application views,
outputs, and inputs. Points to be addressed include such questions as:
Is the description accurate? If not, what aspects of the description must be corrected?
Does the model y support y the y end-user y requirements? y If y not, y what y aspects y of y the
y end-useryrequirements yhave ynot ybeen yaddressed yor yhave ybeen yaddressed
yinadequately?
Keep y in ymind ythat y even y a ymodel y that y perfectly y addresses y all y initially y determined yend y user
y requirements yis ylikely yto yneed yadjustments yas ythose yend yusers ybegin yto yunderstand ythe
yramifications yof ythe ydatabase ydesign's ycapabilities. yIn ymany ycases, ythe yend yusers ymay ylearn
ywhat ythe yorganization's yprocesses yand yprocedures yactually yare, ythus yleading yto ynew
yrequirements yand ythe yperception yof ynew yopportunities. yThe ydatabase ydesigner ymust ykeep ysuch
ylikely ydevelopments yin ymind, yespecially yif y(s)he yworks yas ya ydatabase ydesign yconsultant.
y(Anticipation yof ysuch ydevelopments ymust ybe yfactored yinto ythe ycontract ynegotiations yfor
yconsulting yfees.)
1
, Appendix C The University Lab:
Conceptual Design Verification, Logical Design, and Implementation
Discuss ythe yrole yof ythe ysystem ymodules.
2
, Appendix C The University Lab:
Conceptual Design Verification, Logical Design, and Implementation
The y use y of y system y modules y can y hardly y be y overemphasized y in y a y database y design
y environment. y Stressythese ymodule ycharacteristics yand yfeatures:
Modules yrepresent ysubsets yof ythe ydatabase ymodel: ySmaller y"pieces" yare ymore yeasily
yunderstood.
Modules yare yself-contained yand yaccomplish ya yspecific ysystem yfunction; yif ysuch ya
ysystem yfunction ymust ybe ymodified, yother yfunctions yremain yunaffected.
Modules yfit yinto ya ymodular ydatabase ydesign, ywhich yis ymore yeasily ymodified yand
yadapted yto ynew ycircumstances. yBecause ymodification yefforts yare yfocused yon ya
ydatabase ysubset, yproductivity yof yboth ydesigners yand yapplication ydevelopers yis ylikely
yto ybe yenhanced.
Module yinterfaces ymust ybe yclear yif ythe ymodules yare yexpected yto ywork ywell ywithin ythe yoverall ysystem.
3
, Appendix C The University Lab:
Conceptual Design Verification, Logical Design, and Implementation
Answers yto yReview yQuestions
1. Why ymust ya yconceptual ymodel ybe yverified? yWhat ysteps yare yinvolved yin ythe yverification yprocess?
The yverification yof ya yconceptual ymodel yis ycrucial yto ya ysuccessful ydatabase ydesign. yThe
yverification yprocess yallows ythe ydesigner yto ycheck ythe yaccuracy yof ythe ydatabase ydesign yby:
Re-examining ydata yand ydata ytransformations.
Enabling y the y designer y to y evaluate y the y design y efficiency y relative y to y the y end
y user's y andysystem's ydesign ygoals.
Keep yin ymind ythat, yto ya ylarge yextent, ythe ybest ydesign yis ythe yone ythat yserves ythe y end-user
yrequirements ybest. yFor yexample, ya ydesign ythat yworks ywell yfor ya ymanufacturing yfirm ymay
ynot yfit ythe yneeds yof ya ymarketing yresearch yfirm, yand yvice yversa.
The yverification yprocess yhelps ythe ydesigner yto yavoid yimplementation yproblems ylater yby:
Validating ythe ymodel's yentities. y(Remember ythe yminimal ydata yrule.)
Confirming yentity yrelationships yand yeliminating yduplicate, yunnecessary, yor
yimproperlyydefined yrelationships.
Eliminating ydata yredundancies.
Improving ythe ymodel's ysemantic yprecision yto ybetter yrepresent yreal-world yoperations.
Confirming ythat yall yuser yrequirements y(processing, yperformance, yor ysecurity) yare ymet.
Verification yis ya ycontinuous yactivity yin yany ydatabase ydesign. yThe ydatabase ydesign yprocess yis
yevolutionary yin ynature: yIt yrequires ythe ycontinuous yevaluation yof ythe ydeveloping ymodel yby
yexamining ythe yeffect yof yadding ynew yentities yand yby yconfirming ythat yany ydesign ychanges
yenhance ythe ymodel's yaccuracy.
The yverification yprocess yrequires ythe yfollowing ysteps:
1. Identify ythe ydatabase's ycentral yentity.
The y central y entity y is y the y most y important y entity y in y our y database, y and y most
y of y the y otheryentities ydepend yon yit.
4
Conceptual Design Verification, Logical Design, and Implementation
Appendix C
The University Lab: Conceptual Design,
Verification, Logical Design, and
Implementation
Discussion Focus
How is a database design verified, and why is such verification necessary?
Use our detailed answer to question 1 to focus class discussion on database design verification. Stress
that the verification process uses the initial ER model as a communication tool.
The designer may begin the verification process by describing the organization's operations to its end
users, basing the detailed description on the initial ER model. Next, explain how the operations will be
supported by the database design. Stress that the design must support the end-user application views,
outputs, and inputs. Points to be addressed include such questions as:
Is the description accurate? If not, what aspects of the description must be corrected?
Does the model y support y the y end-user y requirements? y If y not, y what y aspects y of y the
y end-useryrequirements yhave ynot ybeen yaddressed yor yhave ybeen yaddressed
yinadequately?
Keep y in ymind ythat y even y a ymodel y that y perfectly y addresses y all y initially y determined yend y user
y requirements yis ylikely yto yneed yadjustments yas ythose yend yusers ybegin yto yunderstand ythe
yramifications yof ythe ydatabase ydesign's ycapabilities. yIn ymany ycases, ythe yend yusers ymay ylearn
ywhat ythe yorganization's yprocesses yand yprocedures yactually yare, ythus yleading yto ynew
yrequirements yand ythe yperception yof ynew yopportunities. yThe ydatabase ydesigner ymust ykeep ysuch
ylikely ydevelopments yin ymind, yespecially yif y(s)he yworks yas ya ydatabase ydesign yconsultant.
y(Anticipation yof ysuch ydevelopments ymust ybe yfactored yinto ythe ycontract ynegotiations yfor
yconsulting yfees.)
1
, Appendix C The University Lab:
Conceptual Design Verification, Logical Design, and Implementation
Discuss ythe yrole yof ythe ysystem ymodules.
2
, Appendix C The University Lab:
Conceptual Design Verification, Logical Design, and Implementation
The y use y of y system y modules y can y hardly y be y overemphasized y in y a y database y design
y environment. y Stressythese ymodule ycharacteristics yand yfeatures:
Modules yrepresent ysubsets yof ythe ydatabase ymodel: ySmaller y"pieces" yare ymore yeasily
yunderstood.
Modules yare yself-contained yand yaccomplish ya yspecific ysystem yfunction; yif ysuch ya
ysystem yfunction ymust ybe ymodified, yother yfunctions yremain yunaffected.
Modules yfit yinto ya ymodular ydatabase ydesign, ywhich yis ymore yeasily ymodified yand
yadapted yto ynew ycircumstances. yBecause ymodification yefforts yare yfocused yon ya
ydatabase ysubset, yproductivity yof yboth ydesigners yand yapplication ydevelopers yis ylikely
yto ybe yenhanced.
Module yinterfaces ymust ybe yclear yif ythe ymodules yare yexpected yto ywork ywell ywithin ythe yoverall ysystem.
3
, Appendix C The University Lab:
Conceptual Design Verification, Logical Design, and Implementation
Answers yto yReview yQuestions
1. Why ymust ya yconceptual ymodel ybe yverified? yWhat ysteps yare yinvolved yin ythe yverification yprocess?
The yverification yof ya yconceptual ymodel yis ycrucial yto ya ysuccessful ydatabase ydesign. yThe
yverification yprocess yallows ythe ydesigner yto ycheck ythe yaccuracy yof ythe ydatabase ydesign yby:
Re-examining ydata yand ydata ytransformations.
Enabling y the y designer y to y evaluate y the y design y efficiency y relative y to y the y end
y user's y andysystem's ydesign ygoals.
Keep yin ymind ythat, yto ya ylarge yextent, ythe ybest ydesign yis ythe yone ythat yserves ythe y end-user
yrequirements ybest. yFor yexample, ya ydesign ythat yworks ywell yfor ya ymanufacturing yfirm ymay
ynot yfit ythe yneeds yof ya ymarketing yresearch yfirm, yand yvice yversa.
The yverification yprocess yhelps ythe ydesigner yto yavoid yimplementation yproblems ylater yby:
Validating ythe ymodel's yentities. y(Remember ythe yminimal ydata yrule.)
Confirming yentity yrelationships yand yeliminating yduplicate, yunnecessary, yor
yimproperlyydefined yrelationships.
Eliminating ydata yredundancies.
Improving ythe ymodel's ysemantic yprecision yto ybetter yrepresent yreal-world yoperations.
Confirming ythat yall yuser yrequirements y(processing, yperformance, yor ysecurity) yare ymet.
Verification yis ya ycontinuous yactivity yin yany ydatabase ydesign. yThe ydatabase ydesign yprocess yis
yevolutionary yin ynature: yIt yrequires ythe ycontinuous yevaluation yof ythe ydeveloping ymodel yby
yexamining ythe yeffect yof yadding ynew yentities yand yby yconfirming ythat yany ydesign ychanges
yenhance ythe ymodel's yaccuracy.
The yverification yprocess yrequires ythe yfollowing ysteps:
1. Identify ythe ydatabase's ycentral yentity.
The y central y entity y is y the y most y important y entity y in y our y database, y and y most
y of y the y otheryentities ydepend yon yit.
4
