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  1. #1
    Join Date
    Jun 2003
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    2

    Question top down vs bottom up

    what are the advantages and disadvantages of top-down & bottom up design method.? Are there any dangers with either method?

    -ganesh

  2. #2
    Join Date
    Sep 2002
    Location
    UK
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    5,171

    Re: top down vs bottom up

    Originally posted by ganesh15
    what are the advantages and disadvantages of top-down & bottom up design method.? Are there any dangers with either method?

    -ganesh
    Wow, that's an open-ended question! I'm not sure how you'd design a database from the bottom up though: it suggests that you'd first identify all the attributes/columns, and then pull them together into tables, then decide how the tables should be related... I've never seen anyone do that (though I suppose that is how normalisation is often taught, in a way).

    I'd say 80% top down, 20% bottom up: mostly, you work from the requirements and go down into details; for some parts (e.g. interfaces with existing systems/databases) you will need to see what already exists and work out how to join that to your model, which is kind of bottom-up.

    I have never started a database design by thinking: "now where shall I start this, top down or bottom up?"

    Perhaps you need to be more specific about what you mean by "design", and what the top down and bottom up approaches mean to you.

  3. #3
    Join Date
    Jun 2003
    Posts
    24
    same thing if you are doing oodb design. except of course you have to deal with methods and inheritance.

    anyways you can use both bottom up or top down depending on who your though process works.
    water water everywhere and the boards did shirnk
    water water everywhere not a drop to drink

  4. #4
    Join Date
    Jul 2003
    Location
    Australia
    Posts
    217
    By bottom-up, he means exactly that.

    Yes, there are people designing databases like that. They start with all

    the attributes and work their way up to tables.

    In that approach, NORMALIZATION is being heavily relied on.

    That's an inferior approach, in my opinion.

    I believe the TOP-DOWN approach is better.

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