IF not EXISTS( SELECT * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'Product' AND  COLUMN_NAME = 'PFC_ID')
begin
	alter table dbo.Product add PFC_ID	int references dbo.ProductFormulCombine(ID) null
end;
IF not EXISTS( SELECT * FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'Product' AND  COLUMN_NAME = 'Prod_ID')
begin
	alter table dbo.Product add Prod_ID	int references dbo.Product(ID) null
end;