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what is data dictionary in DBMS?

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  1. 1. ry The Data Dictionary a quasi-formal grammar for describing the content of data that the software will process and create a notation for describing control data and the values that control data can take, e.g., "on," or "off" a repository that also contains "where-used" / "how used" information a notation that can be represented manually, but is best developed using CASE tools
  2. 2. Building a Data Dictionary Name: Aliases: Where used: How used: Description: Format: the primary name of the composite data item other names for the data item data transforms (processes) that use the composite data item the role of the data item (input, output, temporary storage, etc. a notation for representing content (presented on next slide) specific information about data types, pre-set values (if known)
  3. 3. Data Dictionary Notation Notation = + [ ] { } ( ... ) * ... text ...* n Meaning is composed of and either-or n repetitions of optional data delimits a comment
  4. 4. Data Dictionary Example telephone number integrated office phone system Name: Aliases: Where/How us ed: Description: Format: telephone number phone number, number read-phone-number (input) display-phone-number (output) analyze-long-distance-calls (input) telephone no. = [ local extension | outside no. | 0 ] outside no. = 9 + [ service code | domestic no. ] service code = [ 211 | 411 | 611 | 911 ] domestic no. = ( ( 0 ) + area code ) + local number area code = *three numeral designator* Build the requirements dictionary: alphanumeric data system output
  5. 5. Control Flow Model CFD is a diagram to describe the control flow of a business process, or program. Begin by stripping all the data flow arrows from the DFD Events (solid arrows) and control items (dashed arrows) are added to the diagram Add a window to the CSPEC (contains and STD that is a sequential specification of the behavior) for each bubble.
  6. 6. CFD for Safe Home
  7. 7. State Transition Diagram
  8. 8. Process Activation Table