3个外键到一个表到一列

Question

there are 2 entities: "A" and "B". In essence, "A" there are fields:

 - A_id (PK)
 - B1_id (FK)
 - B2_id (FK)
 - B3_id (FK)

In essence, "B": B_id and other fields. Is it possible to make relationships to the EF and MS one to one, where "B1_id", "B2_id" and "B3_id" are external keys to one property B_id in table "B". If it is possible, then how can I name the navigation properties in class "A", I think there should be three?

Answer 1

You could do something like:

 public class A
    {
        public int Id { get; set; }

        public int B1Id { get; set; }
        public int B2Id { get; set; }
        public int B3Id { get; set; }

        [ForeignKey("B1Id")]
        public B B1 { get; set; }

        [ForeignKey("B2Id")]
        public B B2 { get; set; }

        [ForeignKey("B3Id")]
        public B B3 { get; set; }
    }

    public class B
    {
        public int Id { get; set; }

        public string Name { get; set; }
    }

Answer 2

public class A
{
    public int Id { get; set; }
    //another properties

    public virtual B B1 { get; set; }
    public int B1Id { get; set; }

    public virtual B B2 { get; set; }
    public int B2Id { get; set; }

    public virtual B B3 { get; set; }
    public int B3Id { get; set; }
}

public class B
{
    public int Id { get; set; }
    //another properties

    [InverseProperty(B1)]
    public virtual ICollection<A> A1 { get; set; }
    [InverseProperty(B2)]
    public virtual ICollection<A> A2 { get; set; }
    [InverseProperty(B3)]
    public virtual ICollection<A> A3 { get; set; }
}