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  1. #1
    Join Date
    Dec 2008
    Posts
    19

    Difference between Conceptual Data Model and Logical Data Model

    Hi,
    can some body explain with diagram
    What is the difference between Conceptual Data Model and Logical Data Model ?

    Thanks

  2. #2
    Join Date
    Feb 2004
    Location
    In front of the computer
    Posts
    15,579
    If you check this link and this one too, you should be able to work it out on your own pretty quickly.

    -PatP

  3. #3
    Join Date
    Dec 2007
    Location
    London, UK
    Posts
    741
    Ignore the advice to "Google it" if you truly want to learn. The curse of Google's PageRank is that you'll get what's popular (read "lazy") not what's right. So the first reference from Googling "Logical Data Model" is Wikipedia (surprise, surprise). Among Wikipedia's gems of random nonsense: a "key difference" between a physical and a logical model is that a physical model "Includes primary keys and indices for fast data access" and a logical one "Is normalized to 4th normal form". This would be funny if it wasn't for the fact that some people actually rely on such drivel to educate themselves.

    Read a decent book such as the excellent one by Terry Halpin: "Information Modelling and Relational Databases".

  4. #4
    Join Date
    Feb 2004
    Location
    In front of the computer
    Posts
    15,579
    Sorry, it appears that dportas missed my point entirely.

    Don't post your homework for others to do it for you. While I used to be in favor of helping students "get started" and overly generous in that area, an administrator at one of the places that I taught pointed out that I was actually sabotaging an important part of the learning process by doing that... You really need to learn how to think critically and how to plan to solve problems.

    If others provide you with anything that you should have derived yourself, they are helping you avoid important parts of the learning process that you are paying your school to impart. You need to learn to think about problems where you don't already know the answer, and find or devise ways to solve those problems. If someone else gives you an answer or even a plan for finding an answer, that person has stolen a learning opportunity from you.

    If you have a problem and you need help, that is Ok. Explain your problem and the steps you have taken to try to solve the problem, then ask for comments or suggestions about the steps you've taken. This lets you get insight from others about your process, and that is constructive. If you simply ask for a solution or guidance on how to reach a solution, then you are effectively giving up on the opportunity to learn.

    Asking for help or analysis of what you've already done is fine, and can be a real learning opportunity. Asking someone else to do all or part of your work for you is a waste of your schooling and their time.

    -PatP

  5. #5
    Join Date
    Dec 2008
    Posts
    19
    is it specifying entities and relations between them ?

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