What Do the Boxes and Lines Mean?

For the past several posts I have been listing tetrads in juxtaposition to a set of graphics:

idef1x.jpg

 

These four graphics are representative of the four fundamental relationships in the relational model using a notational style called IDEF1X.  These four relationships are used to design relational databases.  I am of the opinion that these relationships form what I call a “tetrad”, a term I borrow from Marshall McLuhan, and that it shares characteristics with other tetrads.

I invite you to look at the other posts under the tetrad category in my blog.

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