public long insert(Account entity)
 {
     try
     {
         entity.CreatedAt = DateTime.Now;
         entity.Status = true;
         db.Accounts.Add(entity);
         db.SaveChanges();
         return entity.id;
     }
     catch
     {
         return -1;
     }
 }
 public bool update(Account entity)
 {
     try
     {
         Account a = db.Accounts.Find(entity.id);
         a.Address = entity.Address;
         a.Avatar = entity.Avatar;
         a.DayOfBirth = entity.DayOfBirth;
         a.Email = entity.Email;
         a.Facebook = entity.Facebook;
         a.Fullname = entity.Fullname;
         a.GroupId = entity.GroupId;
         a.ModifiedAt = DateTime.Now;
         a.ModifiedBy = entity.ModifiedBy;
         a.Password = entity.Password;
         a.Phone = entity.Phone;
         a.Roles = entity.Roles;
         a.Skype = entity.Skype;
         a.Status = entity.Status;
         a.Username = entity.Username;
         a.Yahoo = entity.Yahoo;
         db.SaveChanges();
         return true;
     }
     catch
     {
         return false;
     }
 }