public class BaseContext<TContext>
    : DbContext where TContext : DbContext
    {
        static BaseContext()
        {
            Database.SetInitializer<TContext>(null);
        }
        protected BaseContext()
            : base("connectionString")
        { }        
    }

    public class Admin 
    {
        public Guid ID { get; set; }
        public string Name { get; set; }
        public string Pass { get; set; }
    }

    public class UserContext : BaseContext<UserContext>
    {
        public DbSet<Admin> Admins { get; set; }
    }