Chapter 5 Notes - DataResource Management Chapter5...

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Data Resource  Management Chapter 5 Instructed By Jing Yang
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Learning Objectives Principles of Information Systems, Fifth Edition Definition of Database Comparison between traditional DBMT and contemporary DBMT Data Modeling and Database Models Database Basics Database Management
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Fundamental Data Concepts Character Single alphabetic, numeric, or other symbol Field or data item Attribute (characteristic or quality) of some entity (object, person, place, event) Record Grouping of all the fields about an entity File A table or flat file Database An integrated collection of logically related data elements
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Key field, Entity and Attribute
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For example…
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Electric Utility Database
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The Traditional versus the Database Approach  to Data Management
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Fig 5.3
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Problems with the “Traditional” Approach Data redundancy Program-data dependence Inflexibility
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Fig 5.4
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The advantages of Database Approach
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Table 5.2
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Data Modeling & Database Models
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Data Design Issues Content: What data should be collected? Access: What data should be given to what users? Logical structure: How will the data be organized to make sense to a particular user? Physical organization: Where will the data actually be located?
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Data Modeling Logical design shows how data are grouped together and how that are related to one another, in a way that makes sense to users Physical design involves combining or splitting some of the groups identified in the logical design, deciding to maintain summary data in the database, and intentionally storing a data item more than one time. Planned data redundancy is done to improve system performance so that users can get information more quickly Data model a diagram used by a database designer to show the logical relationships among the entities in the database
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Entity-Relationship (ER) Diagrams Fig 5.5
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Database Models Hierarchical Structure Network Structure Relational Structure Object-oriented Structure Multidimensional Structure
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Hierarchical Structure Principles of Information Systems, Fifth Edition A hierarchical database model is a data model in which the data is organized into a tree-like structure. The structure allows representing information using parent/child relationships : each parent can have many children, but each child has only one parent (also known as a 1-to-many relationship ). All attributes of a specific record are listed under an entity type.
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For example…
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Network Structure The network model is a database model conceived as a flexible way of representing objects and their relationships. Its distinguishing feature is that the schema, viewed as a graph in which object types are nodes and relationship types are arcs, is not restricted to being a hierarchy or lattice.
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