$sql = "SELECT t1.id, t1.cmdid,t1.`display_name`,t1.`protocol`,t2.`name` AS tower_name,t3.`name` AS line_name, FROM_UNIXTIME(t4.last_heartbeat) AS last_heartbeat,FROM_UNIXTIME(t4.boot_time) AS boot_time";
$stmt = $db->query("SELECT term_id,battery_voltage,op_temperature,battery_capacity,floating_charge,total_working_time,working_time,connection_state,FROM_UNIXTIME(ws_update_time) AS ws_update_time,signal_strength_4g FROM terminal_working_status_history WHERE term_id=" . $termId . " ORDER BY ws_update_time desc LIMIT 100");