Appendix C The University Lab: b6 b6 b6 b6
Conceptual Design Verification, Logical Design, and
b6 b6 b6 b6 b6
Implementation b6
Appendix C b6
The University Lab: Conceptual Design, b6 b6 b6 b6
Verification,Logical Design, and Implementation
b6 6
b b6 b6 b6
Discussion Focus b6
How is a database design verified, and why is such verification necessary?
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
Use our detailed answer to question 1 to focus class discussion on database design verification.
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
Stress that the verification process uses the initial ER model as a communication tool.
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
The designer may begin the verification process by describing the organization's operations to its
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
end users, basing the detailed description on the initial ER model. Next, explain how the
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
operations will be supported by the database design. Stress that the design must support the
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
end-user application views, outputs, and inputs. Points to be addressed include such questions
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
as:
b6
Is the description accurate? If not, what aspects of the description must be corrected?
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
Does the model support the end-user requirements? If not, what aspects of
b6 b 6 b 6 b 6 b6 b 6 b 6 b 6 b 6 b 6 b 6
b6the end-userrequirements have not been addressed or have been addressed
b 6 b6 b6 b6 b6 b6 b6 b6 b6 b6
inadequately?
b6
Keep in mind that even a model that perfectly addresses all initially determined end user
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
requirements is likely to need adjustments as those end users begin to understand the
b6 6
b b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
ramifications of the database design's capabilities. In many cases, the end users may learn what
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
the organization's processes and procedures actually are, thus leading to new requirements and
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
the perception of new opportunities. Thedatabase designer must keep such likely developments
b6 b6 b6 b6 b6 b6 6
b b6 b6 b6 b6 b6 b6
in mind, especially if (s)he works as a database design consultant. (Anticipation of such
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
developments must be factored into the contract negotiations for consulting fees.)
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
Discuss the role of the system modules.
b6 b6 b6 b6 b6 b6
1
, Appendix C The University Lab: b6 b6 b6 b6
Conceptual Design Verification, Logical Design, and
b6 b6 b6 b6 b6
Implementation b6
The use of system modules can hardly be overemphasized in a database design
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
environment. Stressthese module characteristics and features:
b6 b6 6
b b6 b6 b6 b6
Modules represent subsets of the database model: Smaller "pieces" are more
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
easilyunderstood.
b6 b6
Modules are self-contained and accomplish a specific system function; if such a
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
system function must be modified, other functions remain unaffected.
b6 b6 b6 b6 b6 b6 b6 b6 b6
Modules fit into a modular database design, which is more easily modified and
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
adapted to new circumstances. Because modification efforts are focused on a
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
database subset, productivity of both designers and application developers is likely
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
to be enhanced.
b6 b6 b6
Module interfaces must be clear if the modules are expected to work well within the overall system.
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
2
, Appendix C The University Lab: b6 b6 b6 b6
Conceptual Design Verification, Logical Design, andb6 b6 b6 b6 b6
Implementation b6
Answers to Review Questions
b6 b6 b6
1. Why must a conceptual model be verified? What steps are involved in the verification process?
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
The verification of a conceptual model is crucial to a successful database design. The
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
verification process allows the designer to check the accuracy of the database design by:
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
Re-examining data and data transformations. b6 b6 b6 b6
Enabling the designer to evaluate the design efficiency relative to the end
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
user's andsystem's design goals.
b6 b6 b6 b6 b6
Keep in mind that, to a large extent, the best design is the one that serves the end-user
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b 6
requirements best. For example, a design that works well for a manufacturing firm may not
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
fit the needs of a marketing research firm, and vice versa.
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
The verification process helps the designer to avoid implementation problems later by:
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
Validating the model's entities. (Remember the minimal data rule.)
b6 b6 b6 b6 b6 b6 b6 b6
Confirming entity relationships and eliminating duplicate, unnecessary, or
b6 b6 b6 b6 b6 b6 b6
improperlydefined relationships.
b6 b6 b6
Eliminating data redundancies. b6 b6
Improving the model's semantic precision to better represent real-world operations.
b6 b6 b6 b6 b6 b6 b6 b6 b6
Confirming that all user requirements (processing, performance, or security) are met.
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
Verification is a continuous activity in any database design. The database design process is
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
evolutionary in nature: It requires the continuous evaluation of the developing model by
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
examining the effect of adding new entities and by confirming that any design changes
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
enhance the model's accuracy.
b6 b6 b6 b6
The verification process requires the following steps:
b6 b6 b6 b6 b6 b6
1. Identify the database's central entity. b6 b6 b6 b6
The central entity is the most important
b 6 b 6 b 6 b 6 b 6 b 6 b 6 entity b 6 in our database,
b 6 b 6 b 6 and
most of the otherentities depend on it.
b 6 b 6 b 6 b 6 6
b b6 b6 b6
3
, Appendix C The University Lab: b6 b6 b6 b6
Conceptual Design Verification, Logical Design, and
b6 b6 b6 b6 b6
Implementation b6
2. Identify and define each module and its components.
b6 b6 b6 b6 b6 b6 b6
The designer divides the database model into smaller sets that reflect the
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
data needs ofparticular systems modules such as inventory, orders, payroll, etc.
b6 b6 b6 6
b b6 b6 b6 b6 b6 b6 b6 b6
3. Identify and define each of the module's processes.
b6 b6 b6 b6 b6 b6 b6
Specifically, this step requires the identification and definition of the database transactions
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
that represent the module's real-world operations.
b6 b6 b6 b6 b6
4
Conceptual Design Verification, Logical Design, and
b6 b6 b6 b6 b6
Implementation b6
Appendix C b6
The University Lab: Conceptual Design, b6 b6 b6 b6
Verification,Logical Design, and Implementation
b6 6
b b6 b6 b6
Discussion Focus b6
How is a database design verified, and why is such verification necessary?
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
Use our detailed answer to question 1 to focus class discussion on database design verification.
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
Stress that the verification process uses the initial ER model as a communication tool.
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
The designer may begin the verification process by describing the organization's operations to its
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
end users, basing the detailed description on the initial ER model. Next, explain how the
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
operations will be supported by the database design. Stress that the design must support the
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
end-user application views, outputs, and inputs. Points to be addressed include such questions
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
as:
b6
Is the description accurate? If not, what aspects of the description must be corrected?
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
Does the model support the end-user requirements? If not, what aspects of
b6 b 6 b 6 b 6 b6 b 6 b 6 b 6 b 6 b 6 b 6
b6the end-userrequirements have not been addressed or have been addressed
b 6 b6 b6 b6 b6 b6 b6 b6 b6 b6
inadequately?
b6
Keep in mind that even a model that perfectly addresses all initially determined end user
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
requirements is likely to need adjustments as those end users begin to understand the
b6 6
b b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
ramifications of the database design's capabilities. In many cases, the end users may learn what
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
the organization's processes and procedures actually are, thus leading to new requirements and
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
the perception of new opportunities. Thedatabase designer must keep such likely developments
b6 b6 b6 b6 b6 b6 6
b b6 b6 b6 b6 b6 b6
in mind, especially if (s)he works as a database design consultant. (Anticipation of such
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
developments must be factored into the contract negotiations for consulting fees.)
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
Discuss the role of the system modules.
b6 b6 b6 b6 b6 b6
1
, Appendix C The University Lab: b6 b6 b6 b6
Conceptual Design Verification, Logical Design, and
b6 b6 b6 b6 b6
Implementation b6
The use of system modules can hardly be overemphasized in a database design
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
environment. Stressthese module characteristics and features:
b6 b6 6
b b6 b6 b6 b6
Modules represent subsets of the database model: Smaller "pieces" are more
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
easilyunderstood.
b6 b6
Modules are self-contained and accomplish a specific system function; if such a
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
system function must be modified, other functions remain unaffected.
b6 b6 b6 b6 b6 b6 b6 b6 b6
Modules fit into a modular database design, which is more easily modified and
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
adapted to new circumstances. Because modification efforts are focused on a
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
database subset, productivity of both designers and application developers is likely
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
to be enhanced.
b6 b6 b6
Module interfaces must be clear if the modules are expected to work well within the overall system.
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
2
, Appendix C The University Lab: b6 b6 b6 b6
Conceptual Design Verification, Logical Design, andb6 b6 b6 b6 b6
Implementation b6
Answers to Review Questions
b6 b6 b6
1. Why must a conceptual model be verified? What steps are involved in the verification process?
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
The verification of a conceptual model is crucial to a successful database design. The
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
verification process allows the designer to check the accuracy of the database design by:
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
Re-examining data and data transformations. b6 b6 b6 b6
Enabling the designer to evaluate the design efficiency relative to the end
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
user's andsystem's design goals.
b6 b6 b6 b6 b6
Keep in mind that, to a large extent, the best design is the one that serves the end-user
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b 6
requirements best. For example, a design that works well for a manufacturing firm may not
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
fit the needs of a marketing research firm, and vice versa.
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
The verification process helps the designer to avoid implementation problems later by:
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
Validating the model's entities. (Remember the minimal data rule.)
b6 b6 b6 b6 b6 b6 b6 b6
Confirming entity relationships and eliminating duplicate, unnecessary, or
b6 b6 b6 b6 b6 b6 b6
improperlydefined relationships.
b6 b6 b6
Eliminating data redundancies. b6 b6
Improving the model's semantic precision to better represent real-world operations.
b6 b6 b6 b6 b6 b6 b6 b6 b6
Confirming that all user requirements (processing, performance, or security) are met.
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
Verification is a continuous activity in any database design. The database design process is
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
evolutionary in nature: It requires the continuous evaluation of the developing model by
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
examining the effect of adding new entities and by confirming that any design changes
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
enhance the model's accuracy.
b6 b6 b6 b6
The verification process requires the following steps:
b6 b6 b6 b6 b6 b6
1. Identify the database's central entity. b6 b6 b6 b6
The central entity is the most important
b 6 b 6 b 6 b 6 b 6 b 6 b 6 entity b 6 in our database,
b 6 b 6 b 6 and
most of the otherentities depend on it.
b 6 b 6 b 6 b 6 6
b b6 b6 b6
3
, Appendix C The University Lab: b6 b6 b6 b6
Conceptual Design Verification, Logical Design, and
b6 b6 b6 b6 b6
Implementation b6
2. Identify and define each module and its components.
b6 b6 b6 b6 b6 b6 b6
The designer divides the database model into smaller sets that reflect the
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
data needs ofparticular systems modules such as inventory, orders, payroll, etc.
b6 b6 b6 6
b b6 b6 b6 b6 b6 b6 b6 b6
3. Identify and define each of the module's processes.
b6 b6 b6 b6 b6 b6 b6
Specifically, this step requires the identification and definition of the database transactions
b6 b6 b6 b6 b6 b6 b6 b6 b6 b6 b6
that represent the module's real-world operations.
b6 b6 b6 b6 b6
4
