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

Appendix C The University Lab: b b b b


Conceptual Design Verification, Logical Design, and Implementation b b b b b b




Appendix C b




The University Lab: Conceptual Design, b b b b




b Verification,Logical Design, and Implementation b b b b




Discussion Focus b




How is a database design verified, and why is such verification necessary?
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Use our detailed answer to question 1 to focus class discussion on database design verification. Stress
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that the verification process uses the initial ER model as a communication tool.
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The designer may begin the verification process by describing the organization's operations to its end
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users, basing the detailed description on the initial ER model. Next, explain how the operations will be
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supported by the database design. Stress that the design must support the end-user application views,
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outputs, and inputs. Points to be addressed include such questions as:
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 Is the description accurate? If not, what aspects of the description must be corrected?
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 Does the model support the end-user requirements? If not, what aspects of the
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bend-userrequirements have not been addressed or have been addressed inadequately?
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Keep in mind that even a model that perfectly addresses all initially determined end user
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requirementsis likely to need adjustments as those end users begin to understand the ramifications of
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the database design's capabilities. In many cases, the end users may learn what the organization's
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processes and procedures actually are, thus leading to new requirements and the perception of new
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opportunities. The database designer must keep such likely developments in mind, especially if (s)he
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works as a database design consultant. (Anticipation of such developments must be factored into the
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contract negotiations for consulting fees.)
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Discuss the role of the system modules.
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1

, Appendix C The University Lab: b b b b


Conceptual Design Verification, Logical Design, and Implementation
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The use of system modules can hardly be overemphasized in a database design environment.
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bStressthese module characteristics and features:
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 Modules represent subsets of the database model: Smaller "pieces" are more
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easilyunderstood.
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 Modules are self-contained and accomplish a specific system function; if such a system
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function must be modified, other functions remain unaffected.
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 Modules fit into a modular database design, which is more easily modified and adapted
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to new circumstances. Because modification efforts are focused on a database subset,
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productivity of both designers and application developers is likely to be enhanced.
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Module interfaces must be clear if the modules are expected to work well within the overall system.
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2

, Appendix C The University Lab: b b b b


Conceptual Design Verification, Logical Design, and Implementation
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Answers to Review Questions
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1. Why must a conceptual model be verified? What steps are involved in the verification process?
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The verification of a conceptual model is crucial to a successful database design. The verification
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process allows the designer to check the accuracy of the database design by:
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 Re-examining data and data transformations. b b b b


 Enabling the designer to evaluate the design efficiency relative to the end user's
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andsystem's design goals.
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Keep in mind that, to a large extent, the best design is the one that serves the end-user
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requirements best. For example, a design that works well for a manufacturing firm may not fit the
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needs of a marketing research firm, and vice versa.
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The verification process helps the designer to avoid implementation problems later by:
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 Validating the model's entities. (Remember the minimal data rule.)
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 Confirming entity relationships and eliminating duplicate, unnecessary, or
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bimproperlydefined relationships. b b


 Eliminating data redundancies. b b


 Improving the model's semantic precision to better represent real-world operations.
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 Confirming that all user requirements (processing, performance, or security) are met.
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Verification is a continuous activity in any database design. The database design process is
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evolutionary in nature: It requires the continuous evaluation of the developing model by
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examining the effect of adding new entities and by confirming that any design changes enhance
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the model's accuracy.
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The verification process requires the following steps:
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1. Identify the database's central entity. b b b b




The central entity is the most important entity in our database, and most of
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bthe otherentities depend on it.
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3

, Appendix C The University Lab: b b b b


Conceptual Design Verification, Logical Design, and Implementation
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2. Identify and define each module and its components.
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The designer divides the database model into smaller sets that reflect the data
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bneeds ofparticular systems modules such as inventory, orders, payroll, etc.
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3. Identify and define each of the module's processes.
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Specifically, this step requires the identification and definition of the database transactions
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that represent the module's real-world operations.
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