Insert into select into multiple related tables using INSERT_IDENTITY

Okay setting the scene. I have three tables, (Table1, Table2 and DataTable) and I want to insert into Table1 and Table2 using DataTable as source.
So for every row in DataTable I want a row in Table1 and Table2, and Table2 needs to have the inserted id (PK) from Table1...

If I were to do this...

INSERT INTO Table1 SELECT A, B, C FROM MyTable
INSERT INTO Table2 SELECT IDENTITY_INSERT(), D, E, F FROM MyTable

I'd get the ID of the last inserted record into Table1.

Is a CURSOR or WHILE loop the only ways to do this?

A solution that might work for you is using the OUTPUT clause, which spits out all the inserted rows, so you can re-insert them into a different table. However, this puts limitations on foreign key constraints on Table2, if memory serves.

Anyway, the solution would look something like this:

MERGE INTO Table1 AS t1
USING MyTable ON 1=0 -- always generates "not matched by target"

WHEN NOT MATCHED BY TARGET THEN
    -- INSERT into Table1:
    INSERT (A, B, C) VALUES (t1.A, t1.B, t1.C)

--- .. and INSERT into Table2:
OUTPUT inserted.ID, MyTable.D, MyTable.E, MyTable.F
INTO Table2 (ID, D, E, F);

MERGE, as opposed to the other DML statements, can reference other tables than just inserted and deleted, which is useful for you here.

More: http://sqlsunday.com/2013/08/04/cool-merge-features/

StackExchange Database Administrators Q#73635, answer score: 10