Analyzing Systems Using Data Dictionaries

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Analyzing Systems Using Data Dictionaries

• Keng Siau
• Department of Management
• University of Nebraska -- Lincoln

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Data Dictionaries

• Reference work of data about data (metadata)
• Compiled by systems analysts to guide them
  through analysis and design
• Collects, coordinates, and confirms what a
  specific data term means to different people in
  organization
• Serve as a consistent standard for data elements

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Other Uses of Data Dictionaries

• Validate the data flow diagram for completeness
  and accuracy
• Provide a starting point for developing screens
  and reports
• Determine the contents of data stored in files
• Develop the logic for data flow diagram processes

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Data Dictionary Categories

• Data flows
• Data structures
• Data elements
• Data stores

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Data Flow

• Systems inputs and outputs are determined from
• interviewing
• observing users
• analyzing documents
• analyzing existing systems

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Data Structure

• Usually described using algebraic notation
• Produce a view of the elements that make up the
  data structure
• Algebraic notation
• means is composed of
• means and
• indicates repetitive elements
• indicates either/or situation
• () represents optional element

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Data Element

• Should be defined ONCE in the data dictionary
• Data elements meaning the same thing should be
  listed as Alias

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Data Store

• All base elements must be stored within the
  system
• Derived elements may be stored within the system

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