TO_DATE(TO_CHAR({custrecord_f4n_worked_hours_sales_order.custrecord_f4n_worked_hours_end_time}, 'YYYY-MM-DD HH24:MI:SS'), 'YYYY-MM-DD HH24:MI:SS') - TO_DATE(TO_CHAR({custrecord_f4n_worked_hours_sales_order.custrecord_f4n_worked_hours_start_time}, 'YYYY-MM-DD HH24:MI:SS'), 'YYYY-MM-DD HH24:MI:SS')