Solution Manual for Database Systems Design, Implementation, & Management, 12th Edition Chapter 1-16 with Apendix

Appendix C The University Lab: n n n n




Conceptual Design Verification, Logical Design, and Implementation n n n n n n




Appendix C n




The University Lab: Conceptual Design, Verification,
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Logical Design, and Implementation n n n n




Discussion Focus n




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 that
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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 users,
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basing the detailed description on the initial ER model. Next, explain how the operations will be supported
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by the database design. Stress that the design must support the end-user application views, outputs, and
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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 end-
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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 requirementsis
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likely to need adjustments as those end users begin to understand the ramifications of the database
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design's capabilities. In many cases, the end users may learn what the organization's processes and
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procedures actually are, thus leading to new requirements and the perception of new opportunities. The
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database designer must keep such likely developments in mind, especially if (s)he works as a database
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design consultant. (Anticipation of such developments must be factored into the contract negotiations for
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consulting fees.)
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Discuss the role of the system modules.
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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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Stressthese module characteristics and features:
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• Modules represent subsets of the database model: Smaller "pieces" are more easily
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understood.
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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 tonew
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circumstances. Because modification efforts are focused on a database subset, productivity
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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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Conceptual Design Verification, Logical Design, and Implementation n n n n n n




Answers to Review Questions n n n




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. n n n n




• 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
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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.) n n n n n n n n




• Confirming entity relationships and eliminating duplicate, unnecessary, or improperly
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defined relationships.
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• Eliminating data redundancies. n n




• 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 evolutionary
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in nature: It requires the continuous evaluation of the developing model by examining the effect of
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adding 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. Identify the database's central entity. n n n n




The central entity is the most important entity in our database, and most of the
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notherentities depend on it. n n n n




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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 needs
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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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