Tricky group by date problem

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  • Hugo Kornelis

    #16
    Re: day addition

    On 2 Nov 2006 23:31:55 -0800, boetsid wrote:
    >I saw in one of the solutions
    >select dt + 1 from #anytable --like ( here dt is a
    >datetime field )
    >which one is more efficient or robust between
    >dateadd(day, 1, dt) -- or only using
    >dt + 1
    Hi boetsid,

    Both are equally robust. The behaviour of + with a datetime argument is
    documented in Books Online, so it won't change withour prior warning.

    ms-help://MS.SQLCC.v9/MS.SQLSVR.v9.en/tsqlref9/html/4ba8baac-5f07-432c-87c5-d23e7011da55.ht m,
    example B.

    If you want to know which is more efficient, then set up a loop to
    repeat this calculation a few million times. Run it twice, using the
    different techniques, and compare results. I don't expect that you'll
    find any measurable difference, though.

    --
    Hugo Kornelis, SQL Server MVP

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