Data and process modelling

Chapter 5
Data and Process Modeling




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, Logical Model: Shows what the system must
do, regardless of how it will be implemented
physically
 Physical Model: Describes how the system will
be constructed




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, Systems analysts use graphical techniques to
describe an information system
 Data flow diagram (DFD) - Uses various
symbols to show how the system transforms
input data into useful information




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or duplicated, or posted to a publicly accessible website, in whole or in part. 3

,  A data flow diagram (DFD) shows how data
moves through an information system but
does not show program logic or processing
steps
 A set of DFDs provides a logical model that
shows what the system does, not how it does
it




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or duplicated, or posted to a publicly accessible website, in whole or in part. 4