select a.* from tb_test1 a not exists(select 1 from tb_test2 where b1=a.a1 and b2=a.a2)
select a.* from tb_test1 a left join tb_test2 b on a.a1=b.b1 and a.a2=b.b2
where b.b1 is null
CREATE TABLE tb_test1(a1 int,a2 nvarchar(2))
INSERT INTO tb_test1
SELECT 1 ,'a' UNION ALL
SELECT 1 ,'b' UNION ALL
SELECT 1 ,'c'
CREATE TABLE tb_test2(b1 int,b2 nvarchar(2))
INSERT INTO tb_test2
SELECT 1 ,'a' UNION ALL
SELECT 1 ,'b' UNION ALL
SELECT 1 ,'d' UNION ALL
SELECT 2 ,'c'
SELECT * FROM tb_test1 AS A WHERE A.a2 NOT IN(SELECT b2 FROM tb_test2 AS B WHERE A.a1=B.b1)