Groups > comp.databases.ms-sqlserver > #154

Re: SSE 2008: Trigger: Modifying Data to be Written

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From	Erland Sommarskog <esquel@sommarskog.se>
Newsgroups	comp.databases.ms-sqlserver, microsoft.public.sqlserver.programming
Subject	Re: SSE 2008: Trigger: Modifying Data to be Written
Date	Sat, 09 Apr 2011 11:22:07 +0200
Organization	Erland Sommarskog
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Cross-posted to 2 groups.

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Gene Wirchenko (genew@ocis.net) writes:
>      Thank you. I found an example of INSTEAD OF myself shortly after
> posting.  Half the battle of learning SQL Server is knowing exactly
> what to ask for, and sometimes, it is the tougher half!

I like to add that many developers would prefer to do this with an AFTER 
trigger. This means a higher overhead, because the bad data is first 
written to the table, and then you need to update the target table.
On the other hand, INSTEAD OF triggers gives you a maintainability 
problem. Since you need to redo the original statement, you need to
update the trigger every time you add a column to the table. If you 
forget you may get some headache sorting out what is going on.

What you really want is a BEFORE trigger where you can modify inserted.
But unfortunately SQL Server does not have BEFORE triggers.

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

Links for SQL Server Books Online:
SQL 2008: http://msdn.microsoft.com/en-us/sqlserver/cc514207.aspx
SQL 2005: http://msdn.microsoft.com/en-us/sqlserver/bb895970.aspx

Thread

SSE 2008: Trigger: Modifying Data to be Written Gene Wirchenko <genew@ocis.net> - 2011-04-08 15:11 -0700
  Re: SSE 2008: Trigger: Modifying Data to be Written "Bob Barrows" <reb01501@NOSPAMyahoo.com> - 2011-04-08 18:44 -0400
    Re: SSE 2008: Trigger: Modifying Data to be Written Gene Wirchenko <genew@ocis.net> - 2011-04-08 16:23 -0700
      Re: SSE 2008: Trigger: Modifying Data to be Written Erland Sommarskog <esquel@sommarskog.se> - 2011-04-09 11:22 +0200
        Re: SSE 2008: Trigger: Modifying Data to be Written Gene Wirchenko <genew@ocis.net> - 2011-04-09 21:29 -0700
          Re: SSE 2008: Trigger: Modifying Data to be Written Erland Sommarskog <esquel@sommarskog.se> - 2011-04-10 14:48 +0200
            Re: SSE 2008: Trigger: Modifying Data to be Written Gene Wirchenko <genew@ocis.net> - 2011-04-11 09:46 -0700
          Re: SSE 2008: Trigger: Modifying Data to be Written "Bob Barrows" <reb01501@NOSPAMyahoo.com> - 2011-04-10 08:54 -0400
            Re: SSE 2008: Trigger: Modifying Data to be Written Erland Sommarskog <esquel@sommarskog.se> - 2011-04-10 21:33 +0200
            Re: SSE 2008: Trigger: Modifying Data to be Written Gene Wirchenko <genew@ocis.net> - 2011-04-11 09:42 -0700
              Re: SSE 2008: Trigger: Modifying Data to be Written "Bob Barrows" <reb01501@NOyahooSPAM.com> - 2011-04-11 14:55 -0400
                Re: SSE 2008: Trigger: Modifying Data to be Written Gene Wirchenko <genew@ocis.net> - 2011-04-11 14:53 -0700
                Re: SSE 2008: Trigger: Modifying Data to be Written "Bob Barrows" <reb01501@NOSPAMyahoo.com> - 2011-04-11 18:49 -0400

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