Draw ERD (entity-relationship diagram) & DFD(data flow diagrams) Diagram

timer Asked: Oct 13th, 2015
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Problem: Design an access card system for a building

This building requires access cards to enter its front door. A card reader will read the access card, get the card information, check whether the card has permission to enter, and then ask the cardholder to enter the password. If the card has permission and the corresponding password is correct, the card reader sends signals to open the door and records the time of entry. Otherwise, the card reader does not open the door and records the attempt as abnormal.

The cardholders include students, professors and technicians. Different types of cardholders have different card functions. The students only have basic functions: to access the building, and change their personal information (including passwords). The professors have the basic functions and can check the building entry information. The technicians have the basic functions; can check the building entry information, and give/cancel permissions to the student cards and professor cards. 


1. Draw the set of necessary data flow diagrams (DFDs) 

2. Draw the entity-relationship diagram (ERD)

3. Data Stores in DFDs must contain the description of the stored data

4. ERD – Each entity should include their attributes and the primary key attribute should be identified

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