public User InsertUser(User user)
 {
     var _user = new DB.User();
     _user.UserName = user.UserName;
     _user.Password = user.Password;
     db.Users.Add(_user);
     db.SaveChanges();
     user.UserId = _user.Id;
     return user;
 }
 public bool UpdateUser(User user)
 {
     var _user = db.Users.Find(user.UserId);
     if (_user != null)
     {
         _user.UserName = user.UserName;
         _user.Password = user.Password;
         db.SaveChanges();
         return true;
     }
     else
         return false;
 }