Re: Multiple tests against the same subquery.

From: Hugo Kornelis (hugo_at_pe_NO_rFact.in_SPAM_fo)
Date: 04/13/04

  • Next message: Eric: "Re: Multiple tests against the same subquery." 
    Date: Tue, 13 Apr 2004 22:20:04 +0200

    On Tue, 13 Apr 2004 08:23:37 -0700, Eric wrote:

    >I'm only selecting the ID column because this whole query is actually a
    >subquery in yet another query. It works perfectly, I am extremely grateful
    >for your expertise!

    Eric,

    Glad I could be of assistance.

    Regarding the quote above - if it is a subquery with (NOT) IN, you
    don't need the DISTINCT. My guess is that removing distinct might
    improve performance (but with performance, the truth is alway in the
    testing); if it is a subquery with (NOT) EXISTS, you could also use
    SELECT * instead of SELECT <somecolumn>. I don't think it changes
    performance on this one, but it often does, so it's a good habit to
    always use SELECT * with (NOT) EXISTS.

    Best, Hugo 

    -- 
(Remove _NO_ and _SPAM_ to get my e-mail address)
  • Next message: Eric: "Re: Multiple tests against the same subquery."

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