BMGT 402 Lecture Notes - Lecture 21: Data Redundancy, Database Design, Unique Key
3 Apr 2017
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BMGT402 Lecture 21 - Chapter 14: Normalization
Purpose of Normalization
oNormalization is a database design technique for producing a set of
suitable relations that support the data requirements of an enterprise
oCharacteristics of a suitable set of relations
The minimal number of attributes necessary to support the data
requirements of the enterprise
Attributes with a close logical relationship are found in the same
relation
Minimal data redundancy with each attribute represented only
once with the important exception of attributes that form all or part
of foreign keys
oBenefits
Easier for the user to access and maintain the data
Take up minimal storage space on the computer
How Normalization Supports Database Design
o
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Problems Associated with Data Redundancy
o
oWhat’s the Difference?
Branch number was included twice in Staff and Branch
Branch Address was added to the StaffBranch combined table to
remove data redundancy
Data Redundancy and Update Anomalies
oMajor aim of relational database design is to group attributes into relations
to minimize data redundancy
oRelations that contain redundant information may potentially suffer from
update anomalies
oTypes of update anomalies include:
Insertion
When a new staff data is added:
oMust provide correct branch details
oPotential source of inconsistency
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Document Summary
Purpose of normalization: normalization is a database design technique for producing a set of suitable relations that support the data requirements of an enterprise, characteristics of a suitable set of relations. The minimal number of attributes necessary to support the data requirements of the enterprise. Attributes with a close logical relationship are found in the same relation. Minimal data redundancy with each attribute represented only once with the important exception of attributes that form all or part of foreign keys: benefits. Easier for the user to access and maintain the data. Take up minimal storage space on the computer. Branch number was included twice in staff and branch. Branch address was added to the staffbranch combined table to remove data redundancy. Data redundancy and update anomalies: major aim of relational database design is to group attributes into relations to minimize data redundancy, relations that contain redundant information may potentially suffer from update anomalies, types of update anomalies include:
