Update Trigger Sql

Posted on 2014-11-05
Last Modified: 2014-11-06
We have a trigger that needs to fire on one single column when it is updated.   The trigger doesn't fire at all...below is the code:
alter TRIGGER [dbo].[Ens_UpConversion]
   ON  [dbo].[ens_phyinv]
    after  UPDATE


      -- SET NOCOUNT ON added to prevent extra result sets from
      -- interfering with SELECT statements.

            declare @item       nvarchar(30),
                        @rowpointer nvarchar(60),
                        @cnt        decimal(18,6)

      if update(count_qty)

            declare cntstat cursor local static for

             select item, rowpointer,count_qty
             from inserted  

             open cntstat

              Fetch next from cntstat into @item,@rowpointer,@cnt  
              while @@fetch_status = 0
                   if ((substring(@item,4,1) in ('1','3') and @cnt <> 0) and ((select us_length from ens_dimmain where item = @item) is not null and (select us_length from ens_dimmain where item = @item) <> 0))
                           begin tran  
                              update ensp
                                    set cal_count = @cnt * us_length / 12
                                    from ens_phyinv ensp
                                      inner join ens_dimmain d on d.item = ensp.item
                                    where ensp.rowpointer = @rowpointer
                                    and ensp.item = @item
                                    if @@error <> 0
                                       commit tran
                                      rollback tran
                        end /*if substring*/
              Fetch next from cntstat into @item,@rowpointer,@cnt  
                  end  /*cursor*/
                  close cntstat
                  deallocate cntstat

       end /*if update(count_qty)*/

Question by:spoye
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LVL 34

Expert Comment

ID: 40424269
How have you confirmed that it is not firing? Is it disabled?

btw, why do you use an cursor?? This should be sufficient:

ALTER TRIGGER [dbo].[Ens_UpConversion] ON [dbo].[ens_phyinv]

    IF UPDATE(count_qty)
            WITH    R AS ( SELECT   I.item ,
                                    I.rowpointer ,
                           FROM     INSERTED I
                           WHERE    ( SUBSTRING(I.item, 4, 1) IN ( '1', '3' )
                                      AND I.count_qty <> 0
                                      AND ( SELECT  us_length
                                            FROM    ens_dimmain
                                            WHERE   item = @item
                                          ) IS NOT NULL
                                      AND ( SELECT  us_length
                                            FROM    ens_dimmain
                                            WHERE   item = @item
                                          ) <> 0
                UPDATE  ensp
                SET     cal_count = R.count_qty * us_length / 12
                FROM    ens_phyinv ensp
                        INNER JOIN ens_dimmain d ON d.item = ensp.item
                        INNER JOIN R ON ensp.rowpointer = R.rowpointer
                                        AND ensp.item = R.item;        

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LVL 40

Expert Comment

ID: 40424270
How do you know it actually does not fire?
You could put a statement in there to raiseerror and see if that happens instead of the cursor code.
Also I would definitely NOT recommend using explicit transactions in SQL and in particular in triggers which are hidden SQL code.
Use BEGIN/TRY/CATCH instead if you really need to do that.
LVL 69

Accepted Solution

Scott Pletcher earned 500 total points
ID: 40424313
The trigger is firing, unless it's disabled.  But explicitly committing a transaction inside a trigger could cause all kinds of issues, since you're already in a transaction when the trigger starts, and SQL Server doesn't have true embedded transactions.

Cursors should be avoided if at all possible, especially inside of triggers.

Try this code instead:

ALTER TRIGGER [dbo].[Ens_UpConversion]
    ON  [dbo].[ens_phyinv]

   if update(count_qty)

        update ensp
             set cal_count = ins.count_qty * d.us_length / 12
             from inserted ins
               inner join deleted del on del.item = ins.item and del.rowpointer = ins.rowpointer
               inner join ens_phyinv ensp on ensp.rowpointer = ins.rowpointer and ensp.item = ins.item
               inner join ens_dimmain d on d.item = ins.item
               --verify that *this* row's count_qty changed before processing it
               isnull(ins.count_qty,-555) <> isnull(del.count_qty,-555) and
               substring(ins.item,4,1) in ('1','3') and
               ins.count_qty <> 0 and
               d.us_length <> 0

   end --if
 GO --end of trigger code
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Author Comment

ID: 40424459
I am not sure why the trigger, I like the way you have it, and we created a Table in the db and tried to insert into it, a simple insert 'One record'.   That table has nothing in it .

Author Comment

ID: 40424968
After SET NOCOUNT ON; we place insert into testable(item) and a simple select 'test1' .   We figured that the table should at least have one value in it, but no luck nothing inserted.  We also had the insert after the IF update(count_qty), hoping that it would insert, still with no luck...
LVL 69

Expert Comment

by:Scott Pletcher
ID: 40425031
The trigger only specifies "AFTER UPDATE".

If you want it to run after INSERTs too, you'd have to code it "AFTER INSERT, UPDATE" and change the logic to match that (since a deleted row will not be available for an INSERT).

Author Comment

ID: 40426068
I will try that thank you

Author Closing Comment

ID: 40426869
Thanks so much this worked!

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