class Program
{
    static Model1 d = new Model1();
    static void Main(string[] args)
    {
        save(); // 1 //success
        save(); // 2 //error
         save("xxx"); //3 //why this got error?, when i check Sql Server Profiler, query same with No 2, error duplicate, it should not be error, because the id is not the same
    }

    private static void save(string id="zzz")
    {
        try
        {
            d.Cage.Add(new Cage()
            {
                CageId = id, // id cant same
                CreatedOn = DateTime.Now,
                UpdatedOn = DateTime.Now,
                Depreciation = 0
            });
            d.SaveChanges();
        }
        catch (Exception)
        {
            Console.WriteLine("Error");
        }
    }
}