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Re: Using a trigger to generate an ID value

Posted by imani_technology_spam@yahoo.com on 09/18/06 22:28

I'm using SQL Server 2005. By the way, the front-end app is an Access
Data Project.

Erland Sommarskog wrote:
> imani_technology_spam@yahoo.com (imani_technology_spam@yahoo.com) writes:
> > Thank you for the response. Please bear in mind that the LabID is the
> > identifiable key; it is the PK for the table.
>
> In such case you cannot use an AFTER trigger. A primary key cannot be NULL,
> so it must have a value when you insert the data. Furthermore, if there is
> no other data to correlate, it's impossible to handle multi-row inserts.
> And a trigger that would reqiure rows to be inserted one at a time, is
> completely indefensible. This could have serious impact the day you
> need to insert many rows.
>
> > Also, I don't understand why LabID = @curyear + @curmax + i.newlabid
> > instead of @curyear + (@curmax + 1).
>
> If you insert 10 rows at the time, you cannot give them all the same
> ID, can you?
>
> > Finally, could you please explain to me why the UNION statements are
> > necessary?
>
> I wanted to test that the trigger actually works with multi-row inserts.
> SELECT UNION is a way to achieve that without using a table to select
> from.
>
> I think it's possible to do this with INSTEAD OF trigger, but then I
> need to know which version of SQL Server you are using.
>
>
> --
> 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

 

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