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Thread: Sequence of rows for SQL with no ORDERBY

  1. #1
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    Sequence of rows for SQL with no ORDERBY

    Let us say the following query returning 5 rows.
    Code:
    SELECT USER_ID FROM CLG_USER WHERE USERNAME = 'DEV2FREESTU4'
    I tried running this a few times and everytime user_id = 100 is what is being returned first and that was the row last created by the application (we capture something like a create_date). Now, can I say that the row that was last created is the one that will be returned first if there is no ORDERBY in the SQL ?

    Thanks.

  2. #2
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    Nope ... the order is essentially random and cannot be relied on.
    David Aldridge,
    "The Oracle Sponge"

    Senior Manager, Business Intelligence Development
    XM Satellite Radio
    Washington, DC

    Oracle ACE

  3. #3
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    The order is not random, but can change. The only way to guarantee an order is to use an ORDER BY.
    Jeff Hunter

  4. #4
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    "essentially random", in thesense that it might as well be, because the point at which the order will change at some future date is not known.
    David Aldridge,
    "The Oracle Sponge"

    Senior Manager, Business Intelligence Development
    XM Satellite Radio
    Washington, DC

    Oracle ACE

  5. #5
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    I suppose the correct word is "chaotic", since the order is deterministic but in practice unpredictable.
    "The power of instruction is seldom of much efficacy except in those happy dispositions where it is almost superfluous" - Gibbon, quoted by R.P.Feynman

  6. #6
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    Wordplay

    I think it's safe to say that Jeff's second sentence is the standard Oracle reply,

    "The only way to guarantee an order is to use an ORDER BY"

    Cheers

    Tim...
    Tim...
    OCP DBA 7.3, 8, 8i, 9i, 10g, 11g
    OCA PL/SQL Developer
    Oracle ACE Director
    My website: oracle-base.com
    My blog: oracle-base.com/blog

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