Insert - Select keeping identity mapping - sql

Question

I have 2 tables, and im trying to insert data from one to another and keepeng the mappings between ids.
I found here someone with the same problem, but the solution isnt good for me.
here is the example:
the two tables
CREATE TABLE [source] (i INT identity PRIMARY KEY, some_value VARCHAR(30))
CREATE TABLE [destination] (i INT identity PRIMARY KEY, some_value VARCHAR(30))
CREATE TABLE [mapping] (i_old INT, i_new INT) -- i_old is source.i value, i_new is the inserted destination.i column
some sample data
INSERT INTO [source] (some_value)
SELECT TOP 30 name
FROM sysobjects
INSERT INTO [destination] (some_value)
SELECT TOP 30 name
FROM sysobjects
Here, i want to transfer everything from source into destination, but be able to keep a mapping on the two tables:
I try to use OUTPUT clause, but i cannot refer to columns outside of the ones being inserted:
INSERT INTO [destination] (some_value)
--OUTPUT inserted.i, s.i INTO [mapping] (i_new, i_old) --s.i doesn't work
SELECT some_value
FROM [source] s
Anyone has a solution for this?

Answer 1

Not sure is it write way but it works :D
MERGE [#destination] AS D
USING [#source] AS s
ON s.i <> s.i
WHEN NOT MATCHED BY TARGET
THEN
INSERT (some_value) VALUES (some_value)
OUTPUT inserted.i, s.i INTO [#mapping] (i_new, i_old);

Answer 2

try this sql below if you don't have permission to modify the tables:
The idea is using a temp table to be a bridge between destination table and the mapping table.
SQL Query:
declare #source table (i INT identity PRIMARY KEY, some_value VARCHAR(30))
declare #destination table (i INT identity PRIMARY KEY, some_value VARCHAR(30))
declare #mapping table (i_old INT, i_new INT) -- i_old is source.i value, i_new is the inserted destination.i column
declare #tempSource table
(
id_source INT identity , source_value VARCHAR(30)
,Id_New int,source_new VARCHAR(30)
)
insert into #source
output inserted.i, inserted.some_value into #tempSource(id_source,source_value)
SELECT TOP 10 name
FROM sysobjects
--select * from #tempsource
insert into #destination
OUTPUT inserted.i, inserted.some_value INTO #tempSource (Id_New,source_new)
select source_value from #tempSource
insert into #mapping
select Id_source, Id_New from
(
select a.id_source, a.source_value
from
#tempSource a
where id_source is not null and source_value is not null
) aa
inner join
(
select a.Id_New, a.source_new
from
#tempSource a
where Id_New is not null and source_new is not null
) bb on aa.source_value = bb.source_new
select * from #mapping
The mapping table result:
i_old i_new
----------- -----------
1 1
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