Interaction Between Instead Of Insert Trigger And Output Clause Of Insert Statement

This problem is being seen on SQL 2005 SP2 + cumulative update 4

I am currently successfully using the output clause of an insert statement to return the identity values for inserted rows into a table variable

I now need to add an "instead of insert" trigger to the table that is the subject of the insert.

As soon as I add the "instead of insert" trigger, the output clause on the insert statement does not return any data - although the insert completes successfully. As a result I am not able to obtain the identities of the inserted rows

Note that @@identity would return the correct value in the test repro below - but this is not a viable option as the table in question will be merge replicated and @@identity will return the identity value of a replication metadata table rather than the identity of the row inserted into my_table

Note also that in the test repro, the "instead of insert" trigger actually does nothing apart from the default insert, but the real world trigger has additional code.

To run the repro below - select each of the sections below in turn and execute them
1) Create the table
2) Create the trigger
3) Do the insert - note that table variable contains a row with column value zero - it should contain the @@identity value
4) Drop the trigger
5) Re-run the insert from 3) - note that table variable is now correctly populated with the @@identity value in the row

I need the behaviour to be correct when the trigger is present

Any thoughts would be much appreciated

aero1


/************************************************
1) - Create the table
************************************************/
CREATE TABLE [dbo].[my_table](
[my_table_id] [bigint] IDENTITY(1,1) NOT NULL,
[forename] [varchar](100) NULL,
[surname] [varchar](50) NULL,
CONSTRAINT [pk_my_table] PRIMARY KEY NONCLUSTERED
(
[my_table_id] ASC
)WITH (PAD_INDEX = OFF, IGNORE_DUP_KEY = OFF, FILLFACTOR = 70) ON [PRIMARY]
)

GO
/************************************************
2) - Create the trigger
************************************************/
CREATE TRIGGER [dbo].[trig_my_table__instead_insert] ON [dbo].[my_table]
INSTEAD OF INSERT
AS
BEGIN

INSERT INTO my_table
(
forename,
surname)
SELECT
forename,
surname
FROM inserted

END

/************************************************
3) - Do the insert
************************************************/

DECLARE @my_insert TABLE( my_table_id bigint )

declare @forename VARCHAR(100)
declare @surname VARCHAR(50)

set @forename = N'john'
set @surname = N'smith'

INSERT INTO my_table (
forename
, surname
)
OUTPUT inserted.my_table_id INTO @my_insert
VALUES( @forename
, @surname
)

select @@identity -- expect this value in @my_insert table
select * from @my_insert -- OK value without trigger - zero with trigger

/************************************************
4) - Drop the trigger
************************************************/

drop trigger [dbo].[trig_my_table__instead_insert]
go

/************************************************
5) - Re-run insert from 3)
************************************************/
-- @my_insert now contains row expected with identity of inserted row
-- i.e. OK