Groups > comp.databases.ms-sqlserver > #1841

Re: CASE issue

Path	csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!eu.feeder.erje.net!news.swapon.de!eternal-september.org!feeder.eternal-september.org!mx02.eternal-september.org!.POSTED!not-for-mail
From	Erland Sommarskog <esquel@sommarskog.se>
Newsgroups	comp.databases.ms-sqlserver
Subject	Re: CASE issue
Date	Mon, 24 Nov 2014 11:26:09 +0000 (UTC)
Organization	Erland Sommarskog
Lines	27
Message-ID	<XnsA3EF7E8B63B6CYazorman@127.0.0.1> (permalink)
References	<547306f8$0$41749$c3e8da3$5d8fb80f@news.astraweb.com>
Mime-Version	1.0
Content-Type	text/plain; charset=us-ascii
Content-Transfer-Encoding	7bit
Injection-Date	Mon, 24 Nov 2014 11:26:09 +0000 (UTC)
Injection-Info	mx02.eternal-september.org; posting-host="5d404a5d864426cbf50ddbcd9433a6e4"; logging-data="11005"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX191gaTgMYyYzwQ0ZpSEUJgw"
User-Agent	Xnews/2005.10.03 Mime-proxy/1.4.c.4 (Win32)
Cancel-Lock	sha1:22VHgRddzZGMjmOGMMwEIaIuVqE=
Xref	csiph.com comp.databases.ms-sqlserver:1841

Show key headers only | View raw

twenty-six@b-mint.net (twenty-six@b-mint.net) 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.


-- 
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se

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

Back to comp.databases.ms-sqlserver | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

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

csiph-web