IST352 - Lab 4 Data Normalization Visio 2010(1)-1

IST352 - Lab 4 Data Normalization Visio 2010(1)-1 - IST352...

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IST352 – Information Analysis of Organizational Systems Lab 4 Data Normalization Spring 2012 Data Normalization There are varying degrees of database design quality. They range from one or two great designs, a few good designs and unfortunately many very bad designs. During the data modeling portion of logical design, we employ a process called data normalization that puts us on the path towards great design. So what is data normalization? Data normalization is the process of logically assigning attributes to entities. These are the very same attributes that you gather during the user interviews, surveys and site observations conducted during the analysis phase of the Systems Development Lifecycle. Normalization consists of a number of steps called normal forms. During each normalization step, attributes are carefully placed into your data model in order to achieve an optimum database performance. The reason we normalize data is to reduce data redundancy and consequently as a byproduct we reduce data anomalies; which are errors caused by having duplicate data stored in more than one place. The normalization process does not eliminate redundancy but essentially produces what we call controlled redundancy through the use of primary and foreign keys. Another good reason to reduce redundancy is to save on the use of disk space; therefore, the less data we need to store the less secondary data storage resources we consume. To accomplish the careful placement of data, the systems analyst needs to normalize the data by arranging the data into various states, called normal forms. There are many normal forms but the first three are usually enough to accomplish our goal of good database design. First normal form, sometimes called 1NF, is used to eliminate the repeating attribute groups. The second normal form, or 2NF, removes all attributes that rely on an attribute that is part of the primary key (usually a composite PK) from the result of 1NF and places them in a separate table. Third normal form or 3NF removes all attributes that do not rely on either part of the primary key, but is either dependent on a non-key attribute or has no candidate key to become a primary key in its new table, so a PK has to be created. These attributes and the newly created primary key then become a new table. In this lab exercise, we will continue to explore Visio’s basic features for building a normalized data model using Entity-Relationship Diagrams or ERDs. Materials needed to do this Lab Microsoft Visio Learning Objectives The student will learn to: 1. Explain data normalization and why is it important 2. Explain how normalization helps reduce redundancy and anomalies 3. Use normalization steps to transform from one normal form to the next 4. Use normalization with Entity Relationship modeling to produce good database design 5. Use functions and features of Microsoft Visio
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IST352 – Information Analysis of Organizational Systems Lab 4 Data Normalization Spring 2012
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IST352 - Lab 4 Data Normalization Visio 2010(1)-1 - IST352...

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