Test the logical model

Are all functions possible with this logical model?

Run through all functions, using the UNF sources, that the system must be able to handle.

  • Does the database have all required data (UNF check)?
  • Is it possible to find all required values (FNF check)?
  • Are the functions complete? Check this with a CRUD matrix. Does any tabel have at least one function that
    • Creates a row,
    • reads
    • and deletes?

A CRUD matrix

A CRUD matrix (Create, Read, Update, Delete) is a handy tool for the completeness check. Put tables on one axes, and functions on the other one.
  Newspaper Area Reader Subscription
Foundation C      
Price increase U      
Going broke D     D
Construction   C    
Street name change   U    
Demolition   D    
Subscribe R   C C
Move     U  
Cancel     D D
Print route for newspaper boy R R R R


Start filling the matrix with the C's (create). You'll quickly have a good completeness check.

The CRUD matrix forces you to have a deep thought about the design. It's an excellent preparation for the next step: 3. Technical Optimisation