Groups > comp.databases.ms-sqlserver > #1842

Re: CASE issue

Newsgroups	comp.databases.ms-sqlserver
Date	2014-11-24 04:16 -0800
References	<547306f8$0$41749$c3e8da3$5d8fb80f@news.astraweb.com> <XnsA3EF7E8B63B6CYazorman@127.0.0.1>
Message-ID	<3fc10276-8769-4885-ad67-1a5aee9dbb5c@googlegroups.com> (permalink)
Subject	Re: CASE issue
From	bradbury9 <ray.bradbury9@gmail.com>

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El lunes, 24 de noviembre de 2014 12:26:31 UTC+1, Erland Sommarskog  escribió:
> twenty-six writes:
> > When I run this query I get lots of 'Unknown'  values, but I'm not sure 
> > why. 
> 
> This happens because
> 
>     CASE expr WHEN val1 THEN ....
>               WHEN val2 THEN ....
> 
> is a shortcut for
> 
>    CASE WHEN expr = val1 THEN
>         WHEN expr = val2 THEN
> 
> and thus the expression gets evaluated multiple times and then it goes 
> downhill from there.
> 
> Set up a mapping table instead.
> 

In the MSDN doc it does not mention anything about being a shortcut, and I supposed it was not the case. Good to know that to avoid future errors.

> -- 
> Erland Sommarskog, SQL Server MVP
> 
> Books Online for SQL Server 2005 at
> http://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/books.mspx
> Books Online for SQL Server 2000 at
> http://www.microsoft.com/sql/prodinfo/previousversions/books.mspx

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CASE issue "twenty-six@b-mint.net" <twenty-six@b-mint.net> - 2014-11-24 10:22 +0000
  Re: CASE issue Erland Sommarskog <esquel@sommarskog.se> - 2014-11-24 11:26 +0000
    Re: CASE issue bradbury9 <ray.bradbury9@gmail.com> - 2014-11-24 04:16 -0800
      Re: CASE issue Erland Sommarskog <esquel@sommarskog.se> - 2014-11-24 14:28 +0000
        Re: CASE issue Erland Sommarskog <esquel@sommarskog.se> - 2014-11-28 22:47 +0100
          Re: CASE issue Jim <jgeissman@socal.rr.com> - 2014-11-28 17:19 -0800
    Re: CASE issue "twenty-six@b-mint.net" <twenty-six@b-mint.net> - 2014-11-24 13:32 +0000
      Re: CASE issue Erland Sommarskog <esquel@sommarskog.se> - 2014-11-24 14:25 +0000
        Re: CASE issue "twenty-six@b-mint.net" <twenty-six@b-mint.net> - 2014-11-24 16:06 +0000
    Re: CASE issue Lennart Jonsson <erik.lennart.jonsson@gmail.com> - 2014-11-24 17:18 +0100
      Re: CASE issue Erland Sommarskog <esquel@sommarskog.se> - 2014-11-24 23:37 +0100
        Re: CASE issue Lennart Jonsson <erik.lennart.jonsson@gmail.com> - 2014-11-25 06:25 +0100
          Re: CASE issue Jim <jgeissman@socal.rr.com> - 2014-11-28 16:07 -0800
            Re: CASE issue Erland Sommarskog <esquel@sommarskog.se> - 2014-11-29 10:43 +0100

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