Saving the for data in the database during Updation.

hey guys,
             I am having an edit form with the data getting populated from the search listing form.
The data getting populated is an role and user which gets populated on drop down and text box respectively from the Checked event of grid view in search Listing form.
I want to update the data at the click of Save Button, but i am getting an fatal error occurred during the command execution.
protected void btn_Save_Click(object sender, ImageClickEventArgs e) { MySqlConnection con = new MySqlConnection(ConfigurationManager.ConnectionStrings["fedena_kswa_trngConnectionString"].ConnectionString); con.Open(); MySqlCommand cmd = new MySqlCommand("Update tbl_user_role_mapping Set num_role_id=@num_role_id,dte_updated_at=now() where num_emp_id=@num_emp_id", new MySqlConnection(Confi ...