Databases
StackOverflow2013
Postsdbo
POHow to emulate a BEFORE DELETE trigger in SQL Server 2005
Body
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POHow to emulate a BEFORE DELETE trigger in SQL Server 2005
    text
    copied!<p>Let's say I have three tables, [ONE], [ONE_TWO], and [TWO]. [ONE_TWO] is a many-to-many join table with only [ONE_ID and [TWO_ID] columns. There are foreign keys set up to link [ONE] to [ONE_TWO] and [TWO] to [ONE_TWO]. The FKs use the ON DELETE CASCADE option so that if either a [ONE] or [TWO] record is deleted, the associated [ONE_TWO] records will be automatically deleted as well. </p> <p>I want to have a trigger on the [TWO] table such that when a [TWO] record is deleted, it executes a stored procedure that takes a [ONE_ID] as a parameter, passing the [ONE_ID] values that were linked to the [TWO_ID] before the delete occurred:</p> <pre><code>DECLARE @Statement NVARCHAR(max) SET @Statement = '' SELECT @Statement = @Statement + N'EXEC [MyProc] ''' + CAST([one_two].[one_id] AS VARCHAR(36)) + '''; ' FROM deleted JOIN [one_two] ON deleted.[two_id] = [one_two].[two_id] EXEC (@Statement) </code></pre> <p>Clearly, I need a BEFORE DELETE trigger, but there is no such thing in SQL Server 2005. I can't use an INSTEAD OF trigger because of the cascading FK. </p> <p>I get the impression that if I use a FOR DELETE trigger, when I join [deleted] to [ONE_TWO] to find the list of [ONE_ID] values, the FK cascade will have already deleted the associated [ONE_TWO] records so I will never find any [ONE_ID] values. Is this true? If so, how can I achieve my objective? </p> <p>I'm thinking that I'd need to change the FK joining [TWO] to [ONE_TWO] to not use cascades and to do the delete from [ONE_TWO] manually in the trigger just before I manually delete the [TWO] records. But I'd rather not go through all that if there is a simpler way.</p>
 

Querying!

 
Guidance
An individual column

Larger individual text columns get their own page to allow for proper reading.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload