Detail idea of Data flow Diagram, its rules, with an example. DO LIKE OR COMMENT YOUR FEEDBACK

1. BY- Gagandeep Nanda

2.  It is a graphical representation of the flow of
data.
 It show how the data flow from one process to
other step by step.
 The process detail is not shown in DFD.
 It is notated in by different symbols or boxes:-
1- Yourdon and Coad .
2- Gane and Sarson .

3.  Yourdon and Coad-
Process External entity
Data flow
Data Store

4.  Gane and Sarson-
Process
Data Flow
Data Store
External entity

5.  In DFD the process notation is called black box
EXAMPLE:-
GRADE
STUDENT
WORK
SUBMITTED WORK
GRAD WORK
STUDENT GRAD

6.  SPONTANEOUS Generation
Produces output but no input
Example-
Apply
insurance
premium
Policy Number Payment Amount

7.  Black hole-
Have input but no output
Calculate
Hours Work gross pay Pay Rate

8.  Grey Hole-
Have input and output but input is insufficient to
produce output
Calculate
grade
BOD Final grade

9.  A data storage is a holding place for
information within the system because one or
more process need to use the at a later time
 A DFD does not show detail contents of a data
store

10. Daily payment
Post
payment
Pr3epare
deposit

12.  Physical DFD
 Logical DFD

14. Application
Detail
Confirmation/Rejection
Student
administration
Student
0

15. Check
course
available
Enroll
number
Confirm
Registered
Student
Course
Students
Accepted or not
Registration Detail