Browsing articles tagged with " entity instance diagram"

What the Heck is an Entity Instance Diagram?

Jul 27, 2011   //   by Karen Lopez   //   Blog, Data, Data Modeling, Social Networking  //  4 Comments

I was recently contacted by a friend who is taking a database design course for some help in understanding an assignment.  His first task was to create a conceptual data model and then prepare entity instance diagrams for that data model.  He was wondering what an entity instance diagram was.  So was I, as I had not heard that term before.  So I fired off a search and came up with only one hit:

Google Search for Entity Instance Diagram: 1 hit.

 

I’m pretty sure that’s the first time I’ve every unintentionally found only one returned result for a search term before.  Unfortunately that one webpage has broken images, so I couldn’t see what one looked like.  So I told my friend:

Facebook: Karen Lopez quote

 

I was thinking of examples such as the ones in Simsion & Witt’s  Data Modeling Essentials [aff link]:

 

Sample data table from Data Modeling Essentials.

 

I did some more looking around and using Bing, found one more result which pointed to a PowerPoint slide deck by Ellis Cohen from his course on Theory, Practice & Methodology of Relational Database Design and Programming. In this deck I found an example of what he calls an entity instance diagram, which pretty much is what I thought it was.  I’ve been creating an using these sorts of things to explain how a data model should be used but I never had a name for them.  I called them sample data, data prototypes, data validation , worked examples, or just examples.  Now we have a name and a TLA!

In Cohen’s slide, he’s using an Entity Instance Diagram (EID) to to demonstrate weak entities:

 

Weak Entity Instance Diagram

I usually use Excel to prepare these, as I can reuse the data for each one.  I even have an ER/Studio macro to generate the tabs in a spreadsheet (one for each entity/table selected in a submodel). This makes preparing the sample data go much faster. 

So it looks like we have an answer now for what the heck is an entity instance diagram….and I have a name for a technique that I use all the time.  If you have other examples of this term, I’d love to see them.

 

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