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Modifying Relational View

Last post Thu, Sep 18 2008 12:31 by Matthew Curland. 1 replies.
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  • Thu, Sep 18 2008 11:03

    • rjperes
    • Top 100 Contributor
    • Joined on Thu, Sep 18 2008
    • Posts 4

    Modifying Relational View

    Hi again,

    Will it be possible to work backwards, for example, modifying a Relational View (creating new entities, modifying existing entities, etc) and thus causing the Conceptual Model to be changed accordingly?


     Ricardo Peres

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  • Thu, Sep 18 2008 12:31 In reply to

    Re: Modifying Relational View

    Automatic reverse engineer is only possible for trivial cases. A single relational table can represent multiple ObjectTypes absorbed into that table for subtyping, 1-1 relationships, 1-many objectified relationship, objectified unaries, and a host of other reasons. Similarly, as clearly shown by the Verbalization Browser, a single relational column can map to multiple FactTypes. A process for adding a column to a table and reverse engineering to the conceptual model would require a long list of decision-tree style questions that the user would need to answer. Even then, there would be no guarantee that the column would actually end up in the table you were trying to put it in.

    The relational view (more importantly, the underlying relational model) is a mapped view of the conceptual model. The best thing to do is to navigate to the underlying conceptual ObjectType and add a FactType. The next NORMA drop should make it easier to do the navigation.


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