实体框架如何在同一张表中设置外键为主键

Question

I am writing with the question how to set foreign key to primary key in the same table. Code sample (it does not work "may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.")

 class Employee
        {
            [Key]
            public int EmployeeId { get; set; }
            [ForeignKey("EmployeeId")]
            public int ManagerId { get; set; }               
        }

Answer 1

By [ForeignKey("EmployeeId")] , you declare "EmployeeId" as a foreignKey property name which in the first is declared for the primaryKey by [key] annotation. You should simply change one of these and add a navigation property of your Manager class or remove all data annotations and let Entity Framework takes care of everything.

public class Employee
{
   public int EmployeeId { get; set; }

  //Foreign key for Manager
  public int ManagerId { get; set; }
  public Manager Manager { get; set; }
}

public class Manager
{
   public int ManagerId { get; set; }

   public ICollection<Employee> Employees { get; set; }
}