级联删除 #ef
modelBuilder.Entity<Lodging>().HasRequired(l => l.Destination).WithMany(d => d.Lodgings).WillCascadeOnDelete(true);public class Destination 
{ 
  public int DestinationId { get; set; } 
  public string Name { get; set; } 
  public string Country { get; set; } 
  public string Description { get; set; } 
  public byte[] Photo { get; set; } 
  public List<Lodging> Lodgings { get; set; } 
}
public class Lodging 
{ 
  public int LodgingId { get; set; } 
  public string Name { get; set; } 
  public string Owner { get; set; } 
  public bool IsResort { get; set; } 
  public decimal MilesFromNearestAirport { get; set; } 
  [Required] 
  public Destination Destination { get; set; } }