Topic 5 - Topic 5 Refining the Design This topic...

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Topic 5: Refining the Design This topic illustrates the set of tools that can be used to refine the conceptual database design. One of the widely accepted techniques used in this process is called normalization. Normalization uses a set of rules that are applied to the entities sets and corresponding attributes. This process effectively removes common problems that can arise from poor database design. The normalization process removes redundancy, corrects problems before they occur, and produces a simpler design. Though this is a difficult concept, having basic knowledge on the normalization process makes it easier to understand the use of tables and the SQL language. After reading this topic, you should be able to: Describe the normalization process for refining the database design. Define first normal form (1NF), second normal form (2NF), and third normal form (3NF). Describe anomalies that can occur when tables are not normalized. Discuss the importance of reducing redundancy in a database and the circumstances under which some redundancy is required to improve database performance. Create a set of normalized relational tables that reflect the relationships shown in an ER diagram. Analyze and improve upon a case study database design. Lesson 1: The Importance of Normalization Databases are not simply created and populated with information. Once the database design has been created, a process called normalization should be utilized to help refine the database design. After reading this lesson, you should be able to: Define normalization. Discuss the reasons for normalization. Discuss the importance of tuning the database design before implementing the design. Normalization Once the needs of the organization have been analyzed and the data items required by the organization are identified, the database design can take shape as a set of entities, attributes, and relationships. However, before the implementation effort begins, possible problems in the tentative database design can be identified through the process of normalization. The main objective in developing a logical data model for relational database systems is to create an accurate representation of the data, its relationships, and constraints. To achieve this objective, the designer must identify a suitable set of relations. Normalization is an analytical process that is used to verify that the entities, and the attributes that are assigned to those entities, follow certain design rules for relational databases.
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These normalization rules are defined and discussed in the lessons that follow. If the normalization rules for database design are not enforced, excess data redundancy can occur affecting the efficient use of the database. This data redundancy can cause problems with adding new data, changing data, or deleting data from the database. These update problems are called anomalies. Remember that one of the goals of DBMS is to reduce redundancy and improve
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Topic 5 - Topic 5 Refining the Design This topic...

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