Entity Framework: field of composite key cannot be nullable?

Question

I have a model with composite key - the row is the key:

public class Item
{
    [Key, Column(Order = 0)]
    public int UserId { get; set; }
    [Key, Column         


        

Answer 1

It's not possible with Sql Server, or Oracle for any part of a primary key.

But you can have a unique constraint on these datas.

Which means you can have one time

UserId = 2, Date = null

Then

UserId = 2, Date = 

You can't create directly unique constraints with Code First, but look at SMO.