查询所有的数据，每个小时取一条数据
SELECTid ,DATE_FORMAT(send_time,'%Y-%m-%d %k:00:00') send_time,`sequence`,region_code ,CODE,address,event_type ,water_tmp_val ,ph_val ,diandl_val ,rongy_val ,zhuodu_val
FROMwater_data_item
WHERE1=1 GROUP BYDATE_FORMAT(send_TIME,'%Y-%m-%d %k:00:00')
ORDER BYsend_time DESC