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  1. #1
    Join Date
    Jan 2005
    Posts
    3

    Question When should UML instead of ERM be used as modeling language in the field of DBS?

    A little bit tricky. Anyone knows the answer?

  2. #2
    Join Date
    Sep 2002
    Location
    UK
    Posts
    5,171
    When your client/boss says "this must be done in UML"

  3. #3
    Join Date
    Dec 2004
    Posts
    54

    Unified (Yeah right) Modeling Language

    Hi,
    UML is really touted as a complete methodology that encompasses more than just design. It is a 'collection' of processess and artifacts.

    In the space of 'data' - UML would use class diagrams. Class diagrams focus in on behaviour (functionality) and data together.

    There are inherent problems using class diagrams to model data. Very oftern when you're finished you have to perform 'object to database mappings ' to have something of value.

    One example is that class diagraming allows what is termed many to many associations between classes, whereas in logical data modeling this is considered bad practice.

    The advantage to class diagrams is that you discover the functionality or behavior of classes. There are ways to do this with logical models, but they're not inherent to logical data modeling.

    When or Why to use What - If you're development team is HONESTLY REALLY TRUTHFULLY using object oriented development. (Most places don't really do this) - UML and Class Diagrams work well with this

    If you're using other methods of development (coding) or not true OO.... then you won't gain any advantage in UML.

    Being a data modeler by nature..... I favor logical and physical data models.

    Vmuisc

  4. #4
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
    20,002
    i think the title begs the question

    " ... in the field of DBS" use data models
    Last edited by r937; 01-08-05 at 14:59.
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

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