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  1. #1
    Join Date
    May 2004
    Posts
    7

    Unanswered: Selecting exclusive items (In one table, but not in another)

    Howdy.

    Quick question: How do I select data that is present in one table, but not in another?

    simple example:

    I've got a list of all my people in my phonebook. Another table has a list of the people who I owe money to.

    If I want to do a query on people I can feel free to visit (IE, those in the phonebook, but who I don't owe money too), how would I do this?

    Edit: I probably should mention that I'm using PostgreSQL.
    Last edited by Oberiko; 06-10-04 at 15:21.

  2. #2
    Join Date
    Feb 2004
    Location
    In front of the computer
    Posts
    15,579
    Provided Answers: 54
    Use a left join, and test for NULL values in the foreign key of the table of people you owe money to.

    -PatP

  3. #3
    Join Date
    May 2004
    Posts
    7
    Thanks.

    Just solved it with a NOT IN command.

    <-- Newb. :/

  4. #4
    Join Date
    Feb 2004
    Location
    In front of the computer
    Posts
    15,579
    Provided Answers: 54
    Just FYI, but NOT IN is "expensive" compared to NOT EXISTS. The LEFT OUTER JOIN solution is normally the "cheapest" solution.

    -PatP

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