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Analyzing System Using Data Dictionaries

Analyzing System Using Data Dictionaries. Computer System: Data Dictionary Data Dictionary Categories Creating Data Dictionary. Data Dictionary. a reference data about data metadata keep clean data reduce redundancy collect and coordinates data terms provide documentation.

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Analyzing System Using Data Dictionaries

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  1. Analyzing System Using Data Dictionaries • Computer System: • Data Dictionary • Data Dictionary Categories • Creating Data Dictionary Computer systems

  2. Data Dictionary • a reference • data about data • metadata • keep clean data • reduce redundancy • collect and coordinates data terms • provide documentation Computer systems

  3. Data Repository A larger collection of project information May contain: • information about data • procedural logic and use case • I/O design • data relationships • project requirements and deliverables • project management information Computer systems

  4. Information About Data • data flow • data stores • record structures • elements • entities • messages Computer systems

  5. I/O Design • Screen • Report Computer systems

  6. Data Relationships • data structures • links between data structures Computer systems

  7. Project Management Information • delivery schedules • achievements • issues needed resolving • project users Computer systems

  8. Data Dictionary Categories • Data flows • data structures • data elements • data stores Computer systems

  9. Data Flows Defining the data flows: • ID • Unique descriptive name • general description • source • destination • record entering or leaving • name of the data structure • volume per unit of time • further comments and notations area Computer systems

  10. Data Structures Data structures are usually described: • using algebraic notation • = means “is composed of” • + means “and” • { } indicate repetitive elements • [ ] represent an either/or situation • ( ) represent an optional element Computer systems

  11. Data Structure Syntax • Data Structure (table) • collection of structural records • Structural Record (row) • collection of component elements • component elements (column) • collection of characters Computer systems

  12. Data Structure Example • Customer Name = • First Name + • (Middle Initial) + • Last Name • Method of Payment = • [Check | Charge | Money Order] • Credit Card Type = • [American Express | MasterCard | Visa] Computer systems

  13. Logical Data Structures The data elements used by users such as • name • address • balance due • telephone Logical design stage • reflect user’s view of the system Computer systems

  14. Physical Data Structure Physical data structure includes additional elements used by the system • Key fields • codes identify the status of master records • transaction codes • used to identify types of records • Repeating group entries count • Limits on repeated group • A password for security Computer systems

  15. Data Elements Each data element should be defined once • Element ID • Name of element • Aliases • A short description • Base or derived element • length • data type • I/O format • validation criteria for accuracy • default value • additional comment or remarks area Computer systems

  16. Data Stores Data store description form • data store ID • name • alias for the table • short description • file type: computer or manual • format : database, indexed, sequential, or direct • maximum and average number of records • file or data set name • comment Computer systems

  17. Creating Data Dictionary • Analyzing Input and Output • Developing Data Store Computer systems

  18. I/O Analysis Form The form may contains • Descriptive name • User contact • Input or output file type • Format of data flow • report • screen • undetermined • Elements • sequence • base or derived data • etc. Computer systems

  19. Data Flow / Data Store • Data flow • data in motion • data store • data at rest Computer systems

  20. Employee Paycheck Hours worked 2.1 2.2 General Process BBB 1 General Process BBB 2 Employee DS D3 Data Flow Example Current pay Employee Record Computer systems

  21. Employee Paycheck Hours worked 2.1 2.2 General Process BBB 1 General Process BBB 2 Employee DS D3 Data Dictionary Entries Hours Worked = Employee ID + Hours Current pay amount Employee paycheck = Employee ID + Employee Name + Address + Current pay amount + Pay Date Employee Record Employee Record = Employee ID + Personal Information + Wage Information Computer systems

  22. Using the Data Dictionary may be used to create • screens • reports • forms Computer systems

  23. Extensible Markup Language • Similar to HTML • HTML • formatting document • XML • data sharing between different systems • a way to • define, • sort, • filter, and • translate data into a universal data language Computer systems

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