', 3),
('supplier2', 'product3', 3),
('supplier2', 'product4', 4))
AS Products(supplier_id,..., 1]
-U[supplier1, null, 1]
+U[supplier1, null, 2]
-U[null, null, 1]
+U[null, null, 2]
+I[supplier2,..., 4),
('supplier1', 'product2', 3),
('supplier2', 'product3', 3),
('supplier2', 'product4...1]
+I[supplier1, null, 1]
+I[null, null, 1]
+I[supplier1, product2, 1]
-U[supplier1, null, 1]
+U[supplier1..., null, 2]
+U[null, null, 3]
+I[supplier2, product4, 1]
-U[supplier2, null, 1]
+U[supplier2, null, 2]