Example of code-first entity using Independent association:

public class OrderLine
{
    public int Id { get; set; }
    public decimal Price { get; set; }
    public int Quantity { get; set; }
    public virtual Order Order { get; set; }
}

Example of code-first entity using Foreign key association:

public class  OrderLine
{
    public int Id { get; set; }
    public int OrderId { get; set; }
    public decimal Price { get; set; }
    public int Quantity { get; set; }
    public virtual Order Order { get; set; }
}

C# Event Driven Development