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3.2 DATA & PROCESS MODELLING - Coggle Diagram
3.2 DATA & PROCESS MODELLING
-systems analysts use many graphical techniques to describe an information system
-Data Flow Diagram(DFD) uses various symbols to show how the system transform input data into useful information
-other related tools including data dictionary and process desscription
DATA FLOW DIAGRAM
-show how data moves through an information system but does not show program logic
DFD Symbols
1) process symbols = receives input data and produces output that has a different content, form or both
2) data flow symbol = represents one or more data items
3) data store symbol = represent data that the system stores
4) entity symbol = name of the entity appears inside the symbol
STEP IN CREATING A SET OF DFD
step 1 = draw a content diagram
step 2 = draw a diagram 0 DFD
step 3 = draw the Lowe-Level diagrams
DATA DICTIONARY
-data dictionary, or data repository is a central storehouse of information about the system's data
-an analyst uses the data dictionary to collect, document and organize specific facts about the system
-also defines and describes all data elements and meaningful combinations of data elements
Documenting the Data Elements
Documenting the Data Flows
Documenting the Data Stores
Documenting the Processes
Documenting the Entities
Documenting the Records
Data Dictionary Reports
PROCESS DESCRIPTION
A process description documents the details of a functional primitive, which represents a specific set of processing steps and business logic
Process specification
Structured English
used only the three building blocks of sequence, selection, and iteration
Decision Table
shows a logical structure, with all possible combinations and resulting actions
Modular design
is based on combinations of three logical structures
3 Structure
1) sequence = the completion of the steps in sequential order, one after another
2) selection = the completion of one of two or more process steps based on the results of a test or condition
3) iteration = the completion ofa process step that is repeated until a specific condition changes