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Questions and Answers
What is the purpose of a data dictionary?
What is the purpose of a data dictionary?
What is created for each different data entity being stored?
What is created for each different data entity being stored?
Define 'Data Repository'.
Define 'Data Repository'.
A data repository is a large collection of project information that includes data maintained by the system, procedural logic, screen and report design, data relationships, project requirements, and project management information.
Structural records are groups of elements.
Structural records are groups of elements.
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List two components of describing the data store.
List two components of describing the data store.
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Creating the data dictionary entries is done after the data flow diagram is completed.
Creating the data dictionary entries is done after the data flow diagram is completed.
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In data structures, equal sign means 'is composed of', while braces {} mean ________.
In data structures, equal sign means 'is composed of', while braces {} mean ________.
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Match the following data element characteristics:
Match the following data element characteristics:
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The elements that are present in a data flow coming into or going out of a data store must be contained in the ______.
The elements that are present in a data flow coming into or going out of a data store must be contained in the ______.
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Match the following terms with their descriptions:
Match the following terms with their descriptions:
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Study Notes
Analyzing Systems Using Data Dictionaries
- A data dictionary is a reference work that collects and coordinates data terms, and confirms their meanings to different people in an organization.
- Data dictionaries provide documentation, eliminate redundancy, validate data flow diagrams, and determine the contents of data stored in files.
The Data Repository
- A data repository is a large collection of project information, including:
- Information about the data maintained by the system
- Procedural logic and use cases
- Screen and report design
- Data relationships
- Project requirements and final system deliverables
- Project management information
Data Dictionary Categories
- Data dictionary entries can be categorized into:
- Data flows
- Data structures
- Elements
- Data stores
Defining Data Flows
- A data flow description includes:
- Identification number
- Unique descriptive name
- General description of the data flow
- Source of the data flow
- Destination of the data flow
- Type of data flow
- Name of the data structure describing the elements
- Volume per unit time
- Area for further comments and notations
Describing Data Structures
- Data structures are made up of smaller structures and elements, and are described using algebraic notation.
- Algebraic notation includes:
- Equal sign (=) meaning "is composed of"
- Plus sign (+) meaning "and"
- Braces {} for repetitive elements
- Brackets [] for an either/or situation
- Parentheses () for an optional element
Data Elements
- A data element description includes:
- Element ID
- Name of the element
- Aliases
- Short description of the element
- Element is base or derived
- Element length
- Type of data
- Input and output formats
- Validation criteria
- Default value
- Additional comment or remark area
Data Stores
- A data store description includes:
- Data store ID
- Data store name
- Alias for the table
- Short description of the data store
- File type
- File format
- Maximum and average number of records on the file
- File or data set name
- Data structure
- Primary and secondary keys
- Comments
Creating the Data Dictionary
- Data dictionary entries are created after the data flow diagram is completed or as the data flow diagram is being developed.
- A top-down approach is used to create the data dictionary.
Using the Data Dictionary
- The data dictionary can be used to:
- Create screens, reports, and forms
- Generate computer language source code
- Analyze the system design, detecting flaws and areas that need clarification
Creating XML
- XML is used to exchange data between businesses.
- XML addresses the problem of sharing data when users have different computer systems and software or different database management systems.
- The data dictionary is an ideal starting point for developing XML content.
- XML documents may be transformed into different output formats.
- XML is a way to define, sort, filter, and translate data into a universal data language that can be used by anyone.
XML Document Type Definitions (DTDs)
- DTDs are used to determine if the XML document content is valid.
- DTDs may be created using the data dictionary.
- DTD may be used to validate the XML document.
XML Schemas
- XML schemas provide a more precise way to define the content of an XML document.
- XML schemas include:
- Exact number of times an element may occur
- Type of data within elements
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Description
Learn how to analyze data-oriented systems using data dictionaries and understand the role of CASE tools in creating repositories for project information.
