如题：求助，谁能解释下下面这个mysql语句中的\r\n\t是什么意思
SELECT uid,g_title,g_file,ori_price,price,time_limit,join_num,base_join_num,status,reg_time,supplier_id\r\n\t FROM group_table` \r\n\t  ORDER BY uid DESC \r\n\t  LIMIT 3