Nested Insert query - sql

Question

I'm trying to write a nested insert into query and I want to insert the values, which are inserted in "Table1", in a new table "Table3".
"Table3" has exactly the same columns as "Table1", but without the second insert into value into "Table2".
"Table1" already contains old data, but only the new data inserted in "Table1" should be inserted in "Table3".
-- insert new rows in History
INSERT INTO "table1"
([icao24], [callsign])
SELECT
CurInserts.icao24
,CurInserts.[callsign]
FROM
(
-- INSERT new rows FROM temptable IN currenttable
INSERT INTO "table2"
([icao24], [callsign])
OUTPUT
inserted.[icao24]
,inserted.[callsign]
SELECT
T.[icao24]
,T.[callsign]
FROM #TempTable T
LEFT JOIN "table2" Cur
ON T.[icao24] = Cur.[icao24]
WHERE Cur.[icao24] IS NULL
) CurInserts;

Answer 1

You could first insert the inserted into another table variable or a temporary table.
Then insert into the 2 other tables from the table variable.
Demonstration
declare #tmp table (icao24 int, callsign int);
declare #ins table (icao24 int, callsign int);
insert into #tmp (icao24, callsign) values (1,10),(2,20),(3,30);
insert into #ins (icao24, callsign)
select icao24, callsign
from
(
insert into table1 (icao24, callsign)
output inserted.icao24, inserted.callsign
select tmp.icao24, tmp.callsign
from #tmp tmp
left join table1 t on t.icao24 = tmp.icao24
where t.icao24 is null
) q;
insert into table2 (icao24, callsign)
select icao24, callsign
from #ins;
insert into table3 (icao24, callsign)
select icao24, callsign
from #ins;
select * from table1;
select * from table2;
select * from table3;
icao24 | callsign
-----: | -------:
1 | 10
2 | 20
3 | 30
icao24 | callsign
-----: | -------:
1 | 10
2 | 20
3 | 30
icao24 | callsign
-----: | -------:
2 | 20
3 | 30
Demo on db<>fiddle here