SQL Server 2017

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CREATE TABLE new (
ID INT NULL ,
A INT NULL ,
B INT NULL,
C INT NULL);

INSERT INTO new (ID,A,B,C)
VALUES 
(1,1,1,1),
(2,2,2,2),
(3,3,3,3),
(4,4,4,4),
(5,5,5,5);

SELECT *
FROM new;


ID
A
B
C


1
1
1
1

2
2
2
2

3
3
3
3

4
4
4
4

5
5
5
5


CREATE TABLE old (
ID INT NULL ,
A INT NULL ,
B INT NULL,
C INT NULL);

INSERT INTO old (ID,A,B,C)
VALUES 
(1,1,1,1),
(2,3,2,2),
(3,3,3,3);

SELECT *
FROM old;


ID
A
B
C


1
1
1
1

2
3
2
2

3
3
3
3


SELECT ID,A,B,C
FROM old
UNION 
SELECT ID,A,B,C
FROM new
WHERE new.ID NOT IN (SELECT old.ID
FROM old) 


ID
A
B
C


1
1
1
1

2
3
2
2

3
3
3
3

4
4
4
4

5
5
5
5