Basic Trigger Firing Question

If I insert 20 records into a table which has an INSERT trigger on it, does the trigger fire once for each record, or once at the end of all the inserts?

I seem to be having a problem where the trigger is firing only for some of the inserted records but not others, seemingly randomly (although I know there must be some logical explanation for how it's choosing which record to fire under).

Thanks =) MattHere's how I ended up getting multirow inserts to work properly using an INSTEAD OF trigger rather than a AFTER trigger.

-- INSTEAD OF Trigger That Fires Single-Row AFTER Triggers for a Table with IDENTITY

CREATE TRIGGER trg_T1IOIS ON T1 INSTEAD OF INSERT
AS

SELECT IDENTITY(int, 1, 1) AS key_col, data_col
INTO #t1
FROM inserted

DECLARE @.key AS int
SELECT @.key = MIN(key_col) FROM #t1

WHILE @.key IS NOT NULL
BEGIN

INSERT INTO T1
SELECT data_col FROM #t1 WHERE key_col = @.key

SELECT @.key = MIN(key_col)
FROM #t1
WHERE key_col > @.key

END
GO|||Each Trigger written should be able to deal with either a Single Insert/Delete/update or Bulk Insert/Delete/update

I tend to use the following Format :-

BEGIN
IF @.@.RowCount =1
BEGIN
/*DO SINGLE ROW OPERATION*/
END
ELSE
BEGIN
/*DO MULTI ROW OPERATION*/
END
END

Generally I alter the TSQL to cope with both eventualities
and I believe it is good practice to apply this to ALL Triggers unless of course there are special cicumstances.

Hope this Helps

GW