private void SelectMaintenance()
        {
            try
            {
                using (var sqlConnection = new SqlConnection(connectionString))
                {
                    sqlConnection.OpenAsync();
                    var dynamicParameters = new DynamicParameters();

                    dynamicParameters.Add("work_order", TextBoxWorkOrder.Text, DbType.String, ParameterDirection.Input);
                    dynamicParameters.Add("machine", TextBoxMachine.Text, DbType.String, ParameterDirection.Input);
                    dynamicParameters.Add("employee", TextBoxEmployee.Text, DbType.String, ParameterDirection.Input);
                    dynamicParameters.Add("num_rows", 20, DbType.Int32, ParameterDirection.Input);

                    IEnumerable <ScannerData> result = sqlConnection.Query <ScannerData>(
                        "sp_machine_maint_select",
                        dynamicParameters,
                        commandType: CommandType.StoredProcedure);

                    GridViewMachineMaint.DataSource = result;
                    GridViewMachineMaint.DataBind();
                }
            } catch (Exception e)
            {
                SetErrorMessage("Error: " + e.Message);
            }
        }
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                GridViewMachineMaint.DataSource = null;
                GridViewMachineMaint.DataBind();
                GridViewMachineMaintParts.DataSource = null;
                GridViewMachineMaintParts.DataBind();

                return;
            }
            ;
        }