Systems Analysis and Design
Topic 6: System Dictionary

DEFINITION:


JUSTIFICATION:


USES:


PROCESS:

 


DATA DICTIONARY CATEGORIES:

The data dictionary acts as a repository for the definitions of data flows, data stores, data structures, and data elements.  We're already familiar with data flows and data stores, so...

data element

data structure


DEFINING DATA FLOWS:

Data flows for all input and output should be described first, followed by the internal data flows and the flows to and from data stores.



DEFINING DATA STRUCTURES:

This provides a view of the elements that make up the data structure, and is often described using algebraic notation.  Data structures are necessary whenever multiple data elements must be grouped together to adequately convey a single piece of information. 



DEFINING DATA ELEMENTS: (Each data element should be defined only once in the data dictionary.)




DEFINING DATA STORES:

Data stores are created for each different data entity being stored. A data store is required whenever data elements and data structures are grouped together to form a structural record that must be retained for some period of time.  A data store is created for each unique structural record. 




BENEFITS: