Models.cs

using System.ComponentModel.DataAnnotations;

public abstract class TPCUser
{
    [Key]
    public int Id { get; set; }
    [Required]
    public string Username { get; set; }
    [Required]
    public string Email { get; set; }
}

public class TPCTeacher : TPCUser
{
    public string Designation { get; set; }
    public string Speciality { get; set; }
}

public class TPCStudent : TPCUser
{
    public string CGPA { get; set; }
    public string Major { get; set; }
}