Not able to Add or Update table in Entity Framework 6

I am trying to insert and update table using Entity Framework 6. I am not able to do it.

When i insert, I get an error

Unable to update the EntitySet 'SampleV2' because it has a DefiningQuery and no element exists in the element to support the current operation

When I update, the error thrown is:

The property 'Name' is part of the object's key information and cannot be modified.

My code:

//Table script
CREATE TABLE [dbo].[SampleV2](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [Name] [varchar](150) NOT NULL,
    [DateOfBirth] [datetime] NOT NULL,
    [Status] [bit] NOT NULL
) ON [PRIMARY]

// SampletV2.cs
public partial class SampleV2
{
        public int Id { get; set; }
        public string Name { get; set; }
        public System.DateTime DateOfBirth { get; set; }
        public bool Status { get; set; }
}

// Utilities.cs
public static Dictionary<bool,string> SavePlayerDetails(SampleV2 model)
{
            Dictionary<bool, string> dicInfo = new Dictionary<bool, string>();

            if (model.Id == 0)
            {
                try
                {
                    SampleV2 sam = new SampleV2
                    {
                        Name = model.Name,
                        DateOfBirth = model.DateOfBirth,
                        Status = model.Status
                    };

                    using (var _context = new ExamEntities1())
                    {
                        _context.SampleV2.Add(sam);
                        _context.SaveChanges(); // getting error here
                    }
                }
                catch (Exception e)
                {
                    throw;
                }                
            }
            else
            {
                try
                {
                    using (var _context = new ExamEntities1())
                    {
                        SampleV2 data = _context.SampleV2.SingleOrDefault(a => a.Id == model.Id);
                        data.DateOfBirth = model.DateOfBirth;
                        data.Name = model.Name;
                        data.Status = model.Status;
                        _context.Entry(data).State = System.Data.Entity.EntityState.Modified; // getting error here
                        _context.SaveChanges();
                    }
                }
                catch (Exception e)
                {
                    throw;
                }                
            }            

            return dicInfo;
}