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  • #2307147

    Let’s get back to ER Modelling basics


    by morienr ·

    I think the problem starts right back at the title of the article. Why are we even trying to “solve a many-to-many relationship problem in Microsoft Access”? If we were to go back a further step to the Conceptual Model ie: the ER Model in this case,a M:M relationship is entirely valid, and doesn’t need “solving” in the ER Model. We should apply a simple “transformation” rule to the M:M relationship when mapping it into the Data Model (or Relational Model) – the rule is: A M:M relationship is mapped into a Table – there is no other “relational” way of representing the M:M Relationship in the Relational Model”.

    The fact is, when we are talking about the model in Microsoft Access, we are in fact talking in terms of the Data Model, not the Entity Model. This is also the reason that I object to the statement about the languages spoken being elevated to “entity status”. Frankly, I think that this is a totally misleading concept, and we should be saying that there is no such thing as “entity status”, especially when we are talking about the Data Model.

    This article demonstrates yet again, unfortunately, the confusion and contradiction and ambiguity that is rampant in the ER / Data Modelling world of both practice and literature.No wonder there are so many very badly designed databases out there.

    Let’s get back to ER Modelling basics, and this problem would never have arisen in the first place.

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