Can I keep old keys linked to new keys when making a copy in SQL?

Question

I am trying to copy a record in a table and change a few values with a stored procedure in SQL Server 2005. This is simple, but I also need to copy relationships in other ta

Answer 1

If you need to track both old and new keys in your temp table, you need to cheat and use MERGE:

Data setup:

create table T (
    ID int IDENTITY(5,7) not null,
    Col1 varchar(10) not null
);
go
insert into T (Col1) values ('abc'),('def');

And the replacement for your INSERT statement:

declare @TV table (
    Old_ID int not null,
    New_ID int not null
);
merge into T t1
using (select ID,Col1 from T) t2
on 1 = 0
when not matched then insert (Col1) values (t2.Col1)
output t2.ID,inserted.ID into @TV;

And (actually needs to be in the same batch so that you can access the table variable):

select * from T;
select * from @TV;

Produces:

ID  Col1
5   abc
12  def
19  abc
26  def

Old_ID  New_ID
5       19
12      26

The reason you have to do this is because of an irritating limitation on the OUTPUT clause when used with INSERT - you can only access the inserted table, not any of the tables that might be part of a SELECT.

---

Related - More explanation of the MERGE abuse