Solutions Manual for Database Systems: Design, Implementation, & Management (12th Edition) by Carlos Coronel | Complete Chapter Solutions

Appendix C The UniversityLab: b b b b




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




Appendix C b




TheUniversityLab:ConceptualDesign,Verification, b b b b b




Logical Design,and Implementation b b b b




Discussion Focus b




How is a database design verified,and why issuch verification necessary?
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Use our detailed answer to question 1 to focus class discussion on database design verification. Stress that the
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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 users,
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basing the detailed description on the initial ER model. Next, explain how the operations will be supported by
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the database design. Stress that the design must support the end-user application views, outputs, and inputs.
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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 end-user
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requirements 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 requirements is
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likely to need adjustments as those end users begin to understand the ramifications of the database design's
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capabilities. In many cases, the end users may learn what the organization's processes and procedures
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actually are, thus leading to new requirements and the perception of new opportunities. The database
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designer must keep such likely developments in mind, especially if (s)he works as a database design
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consultant. (Anticipation of such developments must be factored into the contract negotiations for consulting
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fees.)
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Discuss the roleof the system modules. b b b b b b




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, Appendix C The UniversityLab: b b b b




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




The use of system modules can hardly be overemphasized in a database design environment. Stress
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these module characteristics and features:
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• Modules represent subsets of the database model: Smaller "pieces" are more 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 to new
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circumstances. Because modification efforts are focused on a database subset, productivity of
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both designers and application developers is likelyto be enhanced.
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Moduleinterfaces must be clear ifthe modules are expected to work well withinthe overall system.
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, Appendix C The UniversityLab: b b b b




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




Answers to Review Questions b b b




1. Why musta conceptual model be verified? What steps are involved in theverification process?
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The verification of a conceptual model is crucial to a successful database design. The verification process
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allows the designer to check theaccuracy of the database design by:
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• Re-examiningdata and data transformations. b b b b




• Enabling the designer to evaluate the design efficiency relative to the end user's and
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system'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 requirements
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best. For example, a design that works well for a manufacturing firm may not fit the needs of a marketing
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research firm, and vice versa.
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The verification process helps the designerto avoid implementationproblems later by:
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• Validatingthe model's entities. (Remember the minimal data rule.) b b b b b b b b




• Confirming entity relationships and eliminating duplicate, unnecessary, or improperly b b b b b b b b




defined relationships.
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• Eliminating data redundancies. b b




• Improving the model's semantic precision to better represent real-world operations. b b b b b b b b b




• Confirmingthat all user requirements (processing, performance, or security) are met. b b b b b b b b b b




Verification is a continuous activity in any database design. The database design process is evolutionary in
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nature: It requires the continuous evaluation of the developing model by examining the effect of adding
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new entities and by confirming that any design changes enhance the model's accuracy.
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The verification process requires the following steps:
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1. Identifythedatabase's central entity. b b b b




The central entity is the most important entity in our database, and most of the
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otherentities depend on it.
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, Appendix C The UniversityLab: b b b b




Conceptual Design Verification, Logical Design, and Implementation
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2. Identifyand define each module and its components.
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The designer divides the database model into smaller sets that reflect the data needs of
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particular systems modules such as inventory, orders, payroll, etc.
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3. Identifyand 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-worldoperations.
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