Solutions manual for database systems design implementation and management 12th edition by coronel All Chapters 1-16

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 | support | the | end-user | requirements? | If | not, | what | aspects | of | the | end-
user|requirements |have |not |been |addressed |or |have |been |addressed |inadequately?


Keep | in |mind |that | even | a |model | that | perfectly | addresses | all | initially | determined |end | user
| requirements |is |likely |to |need |adjustments |as |those |end |users |begin |to |understand |the |ramifications


|of |the |database |design's |capabilities. |In |many |cases, |the |end |users |may |learn |what |the |organization's


|processes |and |procedures |actually |are, |thus |leading |to |new |requirements |and |the |perception |of |new


|opportunities. |The |database |designer |must |keep |such |likely |developments |in |mind, |especially |if |(s)he


|works |as |a |database |design |consultant. |(Anticipation |of |such |developments |must |be |factored |into |the


|contract |negotiations |for |consulting |fees.)




Discuss |the |role |of |the |system |modules.



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, Appendix |C |The |University |Lab:
Conceptual |Design |Verification, |Logical |Design, |and |Implementation


The | use | of | system | modules | can | hardly | be | overemphasized | in | a | database | design | environment.
| Stress|these |module |characteristics |and |features:




 Modules |represent |subsets |of |the |database |model: |Smaller |"pieces" |are |more |easily
|understood.

 Modules |are |self-contained |and |accomplish |a |specific |system |function; |if |such |a |system
|function |must |be |modified, |other |functions |remain |unaffected.

 Modules |fit |into |a |modular |database |design, |which |is |more |easily |modified |and |adapted |to
|new |circumstances. |Because |modification |efforts |are |focused |on |a |database |subset,

|productivity |of |both |designers |and |application |developers |is |likely |to |be |enhanced.




Module |interfaces |must |be |clear |if |the |modules |are |expected |to |work |well |within |the |overall |system.




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, Appendix |C |The |University |Lab:
Conceptual |Design |Verification, |Logical |Design, |and |Implementation

Answers to Review Questions
| | |




1. Why |must |a |conceptual |model |be |verified? |What |steps |are |involved |in |the |verification |process?


The |verification |of |a |conceptual |model |is |crucial |to |a |successful |database |design. |The |verification
|process |allows |the |designer |to |check |the |accuracy |of |the |database |design |by:




 Re-examining |data |and |data |transformations.
 Enabling | the | designer | to | evaluate | the | design | efficiency | relative | to | the | end | user's
| and|s ystem's |design |goals.




Keep |in |mind |that, |to |a |large |extent, |the |best |design |is |the |one |that |serves |the | end-user
|requirements |best. |For |example, |a |design |that |works |well |for |a |manufacturing |firm |may |not |fit


|the |needs |of |a |marketing |research |firm, |and |vice |versa.




The |verification |process |helps |the |designer |to |avoid |implementation |problems |later |by:

 Validating |the |model's |entities. |(Remember |the |minimal |data |rule.)
 Confirming |entity |relationships |and |eliminating |duplicate, |unnecessary, |or |improperly
|defined |relationships.

 Eliminating |data |redundancies.
 Improving |the |model's |semantic |precision |to |better |represent |real-world |operations.
 Confirming |that |all |user |requirements |(processing, |performance, |or |security) |are |met.


Verification |is |a |continuous |activity |in |any |database |design. |The |database |design |process |is
|evolutionary |in |nature: |It |requires |the |continuous |evaluation |of |the |developing |model |by


|examining |the |effect |of |adding |new |entities |and |by |confirming |that |any |design |changes |enhance


|the |model's |accuracy.




The |verification |process |requires |the |following |steps:



1. Identify |the |database's |central |entity.


The | central | entity | is | the | most | important | entity | in | our | database, | and | most | of
| the | other|entities |depend |on |it.




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, Appendix |C |The |University |Lab:
Conceptual |Design |Verification, |Logical |Design, |and |Implementation


2. Identify |and |define |each |module |and |its |components.


The | designer | divides | the | database | model | into | smaller | sets | that | reflect | the | data
| needs | of|particular |systems |modules |such |as |inventory, |orders, |payroll, |etc.




3. Identify |and |define |each |of |the |module's |processes.


Specifically, | this | step | requires | the | identification | and | definition | of | the | database | transactions
that |represent |the |module's |real-world |operations.




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