SQL Server – Using Source Columns in OUTPUT INTO Clause of INSERT

insertoutput-clause

I am writing a batch processing insert statement and would like to use a temp table to keep track of inserted ID's instead of looping through the items myself and calling SCOPE_IDENTITY() for each inserted row.

The data that needs to be inserted has (temporary) ID's linking it to other data that also should be inserted into another table, so I need a cross reference of the actual Id and the temporary Id.

This is an example of what I have so far:

-- The existing table 
DECLARE @MyTable TABLE (ID INT IDENTITY(1,1), [Name] NVARCHAR(MAX));

-- My data I want to insert
DECLARE @MyInsertData TABLE (ID INT, [Name] NVARCHAR(MAX));
INSERT INTO @MyInsertData ( ID,Name)
VALUES ( -1 , 'bla'),(-2,'test'),(-3,'last');

DECLARE @MyCrossRef TABLE ([NewId] INT, OldId INT);

INSERT INTO @MyTable ( [Name] )
   OUTPUT Inserted.ID, INS.ID INTO @MyCrossRef
   SELECT [NAME] FROM @MyInsertData INS

-- Check the result
SELECT * FROM @MyCrossRef

The problem is that I cannot get the OUTPUT INTO clause to accept the ID, I've tried @MyInsertData.ID and other tricks joining the table to itself, but nothing seems to work.

Best Answer

Actually, you can achieve the same thing by changing your INSERT to a MERGE. While the MERGE statement is actually a pretty neat way to do "upserts" in SQL Server, there's nothing to stop you from using it just for the purpose of inserting:

-- The existing table 
DECLARE @MyTable TABLE (ID INT IDENTITY(1,1), [Name] NVARCHAR(MAX));

-- My data I want to insert
DECLARE @MyInsertData TABLE (ID INT, [Name] NVARCHAR(MAX));
INSERT INTO @MyInsertData ( ID,Name)
VALUES ( -1 , 'bla'),(-2,'test'),(-3,'last');

DECLARE @MyCrossRef TABLE ([NewId] INT, OldId INT);

MERGE INTO @MyTable AS dest
USING @MyInsertData AS ins ON 1=0   -- always false

WHEN NOT MATCHED BY TARGET          -- happens for every row, because 1 is never 0
    THEN INSERT ([Name])
         VALUES (ins.[NAME])

OUTPUT inserted.ID, ins.ID
INTO @MyCrossRef (NewId, OldId);

-- Check the result
SELECT * FROM @MyCrossRef

One of the nice things about MERGE is that it allows you to access the source columns as well as the built-in inserted and deleted tables in the OUTPUT clause.

My code may contain errors, as I haven't actually tested it. My blog post from a few years ago goes into a little more detail, including on query performance.

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