Appendix C The UniversityLab: d d d d
Conceptual Design Verification, Logical Design, and Implementation d d d d d d
Appendix C d
TheUniversityLab:ConceptualDesign,Verification, d d d d d
Logical Design,and Implementation d d d d
Discussion Focus d
How is a database design verified,and why issuch verification necessary?
d d d d d d d d d d d
Use our detailed answer to question 1 to focus class discussion on database design verification. Stress that the
d d d d d d d d d d d d d d d d d
verification process uses the initial ER model as a communication tool.
d d d d d d d d d d d
The designer may begin the verification process by describing the organization's operations to its end users,
d d d d d d d d d d d d d d d
basing the detailed description on the initial ER model. Next, explain how the operations will be supported by
d d d d d d d d d d d d d d d d d d
the database design. Stress that the design must support the end-user application views, outputs, and inputs.
d d d d d d d d d d d d d d d d
Points to be addressed include such questions as:
d d d d d d d d
• Is the description accurate? If not, what aspects of the description must be corrected?
d d d d d d d d d d d d d
• Does the model support the end-user requirements? If not, what aspects of the end-user
d d d d d d d d d d d d d
requirements have not been addressed or have been addressed inadequately?
d d d d d d d d d d
Keep in mind that even a model that perfectly addresses all initially determined end user requirements is
d d d d d d d d d d d d d d d d
likely to need adjustments as those end users begin to understand the ramifications of the database design's
d d d d d d d d d d d d d d d d d
capabilities. In many cases, the end users may learn what the organization's processes and procedures
d d d d d d d d d d d d d d d
actually are, thus leading to new requirements and the perception of new opportunities. The database
d d d d d d d d d d d d d d d
designer must keep such likely developments in mind, especially if (s)he works as a database design
d d d d d d d d d d d d d d d d
consultant. (Anticipation of such developments must be factored into the contract negotiations for consulting
d d d d d d d d d d d d d d
fees.)
d
Discuss the roleof the system modules. d d d d d d
1
, Appendix C The UniversityLab: d d d d
Conceptual Design Verification, Logical Design, and Implementation d d d d d d
The use of system modules can hardly be overemphasized in a database design environment. Stress
d d d d d d d d d d d d d d
these module characteristics and features:
d d d d d
• Modules represent subsets of the database model: Smaller "pieces" are more easilyunderstood.
d d d d d d d d d d d d
• Modules are self-contained and accomplish a specific system function; if such a system
d d d d d d d d d d d d
function must be modified, other functions remain unaffected.
d d d d d d d d
• Modules fit into a modular database design, which is more easily modified and adapted to new
d d d d d d d d d d d d d d d
circumstances. Because modification efforts are focused on a database subset, productivity of
d d d d d d d d d d d d
both designers and application developers is likelyto be enhanced.
d d d d d d d d d d
Moduleinterfaces must be clear ifthe modules are expected to work well withinthe overall system.
d d d d d d d d d d d d d d d d
2
, Appendix C The UniversityLab: d d d d
Conceptual Design Verification, Logical Design, and Implementation d d d d d d
Answers to Review Questions d d d
1. Why musta conceptual model be verified? What steps are involved in theverification process?
d d d d d d d d d d d d d d
The verification of a conceptual model is crucial to a successful database design. The verification process
d d d d d d d d d d d d d d d
allows the designer to check theaccuracy of the database design by:
d d d d d d d d d d d d
• Re-examiningdata and data transformations. d d d d
• Enabling the designer to evaluate the design efficiency relative to the end user's and
d d d d d d d d d d d d d
system's design goals.
d d d
Keep in mind that, to a large extent, the best design is the one that serves the end-user requirements
d d d d d d d d d d d d d d d d d d
best. For example, a design that works well for a manufacturing firm may not fit the needs of a marketing
d d d d d d d d d d d d d d d d d d d d
research firm, and vice versa.
d d d d d
The verification process helps the designerto avoid implementationproblems later by:
d d d d d d d d d d d
• Validatingthe model's entities. (Remember the minimal data rule.) d d d d d d d d
• Confirming entity relationships and eliminating duplicate, unnecessary, or improperly d d d d d d d d
defined relationships.
d d
• Eliminating data redundancies. d d
• Improving the model's semantic precision to better represent real-world operations. d d d d d d d d d
• Confirmingthat all user requirements (processing, performance, or security) are met. d d d d d d d d d d
Verification is a continuous activity in any database design. The database design process is evolutionary in
d d d d d d d d d d d d d d d
nature: It requires the continuous evaluation of the developing model by examining the effect of adding
d d d d d d d d d d d d d d d d
new entities and by confirming that any design changes enhance the model's accuracy.
d d d d d d d d d d d d d
The verification process requires the following steps:
d d d d d d
1. Identifythedatabase's central entity. d d d d
The central entity is the most important entity in our database, and most of the
d d d d d d d d d d d d d d
otherentities depend on it.
d d d d d
3
, Appendix C The UniversityLab: d d d d
Conceptual Design Verification, Logical Design, and Implementation
d d d d d d
2. Identifyand define each module and its components.
d d d d d d d
The designer divides the database model into smaller sets that reflect the data needs of
d d d d d d d d d d d d d d
particular systems modules such as inventory, orders, payroll, etc.
d d d d d d d d d
3. Identifyand define each of the module's processes.
d d d d d d d
Specifically, this step requires the identification and definition of the database transactions
d d d d d d d d d d d
that represent the module's real-worldoperations.
d d d d d
4
Conceptual Design Verification, Logical Design, and Implementation d d d d d d
Appendix C d
TheUniversityLab:ConceptualDesign,Verification, d d d d d
Logical Design,and Implementation d d d d
Discussion Focus d
How is a database design verified,and why issuch verification necessary?
d d d d d d d d d d d
Use our detailed answer to question 1 to focus class discussion on database design verification. Stress that the
d d d d d d d d d d d d d d d d d
verification process uses the initial ER model as a communication tool.
d d d d d d d d d d d
The designer may begin the verification process by describing the organization's operations to its end users,
d d d d d d d d d d d d d d d
basing the detailed description on the initial ER model. Next, explain how the operations will be supported by
d d d d d d d d d d d d d d d d d d
the database design. Stress that the design must support the end-user application views, outputs, and inputs.
d d d d d d d d d d d d d d d d
Points to be addressed include such questions as:
d d d d d d d d
• Is the description accurate? If not, what aspects of the description must be corrected?
d d d d d d d d d d d d d
• Does the model support the end-user requirements? If not, what aspects of the end-user
d d d d d d d d d d d d d
requirements have not been addressed or have been addressed inadequately?
d d d d d d d d d d
Keep in mind that even a model that perfectly addresses all initially determined end user requirements is
d d d d d d d d d d d d d d d d
likely to need adjustments as those end users begin to understand the ramifications of the database design's
d d d d d d d d d d d d d d d d d
capabilities. In many cases, the end users may learn what the organization's processes and procedures
d d d d d d d d d d d d d d d
actually are, thus leading to new requirements and the perception of new opportunities. The database
d d d d d d d d d d d d d d d
designer must keep such likely developments in mind, especially if (s)he works as a database design
d d d d d d d d d d d d d d d d
consultant. (Anticipation of such developments must be factored into the contract negotiations for consulting
d d d d d d d d d d d d d d
fees.)
d
Discuss the roleof the system modules. d d d d d d
1
, Appendix C The UniversityLab: d d d d
Conceptual Design Verification, Logical Design, and Implementation d d d d d d
The use of system modules can hardly be overemphasized in a database design environment. Stress
d d d d d d d d d d d d d d
these module characteristics and features:
d d d d d
• Modules represent subsets of the database model: Smaller "pieces" are more easilyunderstood.
d d d d d d d d d d d d
• Modules are self-contained and accomplish a specific system function; if such a system
d d d d d d d d d d d d
function must be modified, other functions remain unaffected.
d d d d d d d d
• Modules fit into a modular database design, which is more easily modified and adapted to new
d d d d d d d d d d d d d d d
circumstances. Because modification efforts are focused on a database subset, productivity of
d d d d d d d d d d d d
both designers and application developers is likelyto be enhanced.
d d d d d d d d d d
Moduleinterfaces must be clear ifthe modules are expected to work well withinthe overall system.
d d d d d d d d d d d d d d d d
2
, Appendix C The UniversityLab: d d d d
Conceptual Design Verification, Logical Design, and Implementation d d d d d d
Answers to Review Questions d d d
1. Why musta conceptual model be verified? What steps are involved in theverification process?
d d d d d d d d d d d d d d
The verification of a conceptual model is crucial to a successful database design. The verification process
d d d d d d d d d d d d d d d
allows the designer to check theaccuracy of the database design by:
d d d d d d d d d d d d
• Re-examiningdata and data transformations. d d d d
• Enabling the designer to evaluate the design efficiency relative to the end user's and
d d d d d d d d d d d d d
system's design goals.
d d d
Keep in mind that, to a large extent, the best design is the one that serves the end-user requirements
d d d d d d d d d d d d d d d d d d
best. For example, a design that works well for a manufacturing firm may not fit the needs of a marketing
d d d d d d d d d d d d d d d d d d d d
research firm, and vice versa.
d d d d d
The verification process helps the designerto avoid implementationproblems later by:
d d d d d d d d d d d
• Validatingthe model's entities. (Remember the minimal data rule.) d d d d d d d d
• Confirming entity relationships and eliminating duplicate, unnecessary, or improperly d d d d d d d d
defined relationships.
d d
• Eliminating data redundancies. d d
• Improving the model's semantic precision to better represent real-world operations. d d d d d d d d d
• Confirmingthat all user requirements (processing, performance, or security) are met. d d d d d d d d d d
Verification is a continuous activity in any database design. The database design process is evolutionary in
d d d d d d d d d d d d d d d
nature: It requires the continuous evaluation of the developing model by examining the effect of adding
d d d d d d d d d d d d d d d d
new entities and by confirming that any design changes enhance the model's accuracy.
d d d d d d d d d d d d d
The verification process requires the following steps:
d d d d d d
1. Identifythedatabase's central entity. d d d d
The central entity is the most important entity in our database, and most of the
d d d d d d d d d d d d d d
otherentities depend on it.
d d d d d
3
, Appendix C The UniversityLab: d d d d
Conceptual Design Verification, Logical Design, and Implementation
d d d d d d
2. Identifyand define each module and its components.
d d d d d d d
The designer divides the database model into smaller sets that reflect the data needs of
d d d d d d d d d d d d d d
particular systems modules such as inventory, orders, payroll, etc.
d d d d d d d d d
3. Identifyand define each of the module's processes.
d d d d d d d
Specifically, this step requires the identification and definition of the database transactions
d d d d d d d d d d d
that represent the module's real-worldoperations.
d d d d d
4
