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

I've verified that the problem is that you can only use INSERTED columns. The documentation seems to indicate that you can use from_table_name, but I can't seem to get it to work (The multi-part identifier "m.ContentID" could not be bound.):

TRUNCATE TABLE main

SELECT *
FROM incoming

SELECT *
FROM main

DECLARE @Missing TABLE (ContentID INT PRIMARY KEY)
INSERT INTO @Missing(ContentID) 
SELECT incoming.ContentID
FROM incoming
LEFT JOIN main
    ON main.ContentID = incoming.ContentID
WHERE main.ContentID IS NULL

SELECT *
FROM @Missing

DECLARE @Inserted TABLE (ContentID INT PRIMARY KEY, [Content] varchar(50))
INSERT INTO main(ContentID, [Content]) 
OUTPUT INSERTED.ContentID /* incoming doesn't work, m doesn't work */, INSERTED.[Content] INTO @Inserted (ContentID, [Content])
SELECT incoming.ContentID, incoming.[Content] 
FROM incoming
INNER JOIN @Missing AS m
    ON m.ContentID = incoming.ContentID

SELECT *
FROM @Inserted

SELECT *
FROM incoming

SELECT *
FROM main

Apparently the from_table_name prefix is only allowed on DELETE or UPDATE (or MERGE in 2008) - I'm not sure why:

• from_table_name

Is a column prefix that specifies a table included in the FROM clause of a DELETE or UPDATE statement that is used to specify the rows to update or delete.

If the table being modified is also specified in the FROM clause, any reference to columns in that table must be qualified with the INSERTED or DELETED prefix.