What columns can be used in OUTPUT INTO clause?

Question

I\'m trying to build a mapping table to associate the IDs of new rows in a table with those that they\'re copied from. The OUTPUT INTO clause seems perfect for that, but it does

Answer 1

You can do this with a MERGE in Sql Server 2008. Example code below:

--drop table A
create table A (a int primary key identity(1, 1))
insert into A default values
insert into A default values

delete from A where a>=3

-- insert two values into A and get the new primary keys
MERGE a USING (SELECT a FROM A) AS B(a)
ON (1 = 0) -- ignore the values, NOT MATCHED will always be true
WHEN NOT MATCHED THEN INSERT DEFAULT VALUES -- always insert here for this example
OUTPUT $action, inserted.*, deleted.*, B.a; -- show the new primary key and source data

Result is

INSERT, 3, NULL, 1
INSERT, 4, NULL, 2

i.e. for each row the new primary key (3, 4) and the old one (1, 2). Creating a table called e.g. #OUTPUT and adding " INTO #OUTPUT;" at the end of the OUTPUT clause would save the records.