How can i insert the multiple data in table using the existance condition?
INSERT dbo.mytest(first_name, table_id)
SELECT fn, ti FROM 
(
  VALUES('f1', @id_for_test),
        ('f2', @id_for_test),
        ('f3', @id_for_test),
        ('f4', @id_for_test),
        ('f5', @id_for_test),
        ('f6', @id_for_test)
) AS x(fn, ti)
WHERE NOT EXISTS 
(
  SELECT 1 FROM dbo.mytest
    WHERE first_name = x.fn
      AND table_id   = @id_for_test -- or = x.ti
);