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This post addresses denormalization and binary relationships

Question 1.
What is denormalization, and why can it be desirable? Provide an example.

Question 2.
Give examples of binary 1:N relationships, (a) an optional-to-optional relationship, (b) an optional-to-mandatory relationship, (c) a mandatory-to-optional relationship, and (d) a mandatory-to-mandatory relationship. Illustrate using IE Crow's Foot E-R diagrams.

Solution Preview

Question 1.
What is denormalization, and why can it be desirable? Provide an example.
Denormalization is a process of "adding redundant data to get rid of complex join, in order to optimize database performance" (SQL Server, 2010). The process of denormalization is favorable because it increases database access by moving from a higher level of normalization to a lower level of normalization. This is desirable when speed is an issue. When there are multiple table JOINS, a denormalization would optimally take data from one table and use it on another table. By doing so, it would cancel out the need for the additional table, which will reduce the number of necessary JOINS, and therefore speed performance. This is the most common use and benefit of denormalization. The redundant data is added back by the programmer after the normalization process has been completed. It is a reverse process and always involves the moving of data from ...

Solution Summary

The solution provides a detailed explanation with references explaining denormalization and why it can be desirable. The solution also provides a detailed example of binary 1:N relationships, (a) an optional-to-optional relationship, (b) an optional-to-mandatory relationship, (c) a mandatory-to-optional relationship, and (d) a mandatory-to-mandatory relationship. Illustrate using IE Crow's Foot E-R diagrams. Complete references are provided.

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