public string ChangeDoctorPassword(ChangePassword changePassword) { bool validOldPassword = aDoctorGateway.IsOldPasswordValid(changePassword.DoctorId, changePassword.OldPassword); if (validOldPassword) { int rowAffected = aDoctorGateway.ChangeDoctorPassword(changePassword); if (rowAffected > 0) { return("Success"); } else { return("Your password changing failed."); } } else { return("Your old password is wrong. Try again!"); } }