Intro

I have collected Q&A topics since about 2010. These are being put onto this blog gradually, which explains why they are dated 2017 and 2018. Most are responses to questions from my students, some are my responses to posts on the Linkedin forums. You are invited to comment on any post. To create a new topic post or ask me a question, please send an email to: geverest@umn.edu since people cannot post new topics on Google Blogspot unless they are listed as an author. Let me know if you would like me to do that.

2020-03-25

Is a data model a "representation"? ...of what?


Ken Evans asks (LinkedIn, Data modeling, 2020/3/25)
Hmm. Is a data model a "representation"?

EVEREST RESPONDS:

First of all I don't like the phrase "Data Model" (sorry "Ted" Codd).  It suggests that it is a "model of data."  That is misleading to someone outside of our community.  It is only a model of data if we have some data.  Then the model would be an (abstract) "representation" of the data.  For us, a "data" model is a model of some aspects of a domain of interest to a community of users, real (world) or imagined/desired/yet to be built.  It is a model "in data," that is, built using informational constructs, all guided by a modeling scheme.  The modeling scheme tells us what to look for in the domain and how to represent it in the model.  So we identify a population of similar things, give it a label and a definition, and put a box or circle into a diagram to represent that population of things.  We build up or "design" a model with lots of types of things, add relationships among those things, and constraints on those things and relationships.  The modeling scheme tells us how to represent those relationships and constraints in our model.  Graham Witt adds some light to this argument by calling it a "business data model."

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