The relationship could not be changed because one or more of the foreign-key properties is non nullable
In Entity Framework you can work with foreign key associations. That is, a foreign key to another object is expressed as a pair of two properties: a primitive foreign key property (e.g. NominalRouting.OrderItemId) and an object reference (NominalRouting.OrderItem). This means that you can either set a primitive value or an object reference to establish a … Read more