Mysql取每小时的一条记录

SELECT * FROM (
SELECT
s.sensor_data,s.get_date,s.sensor_name,
DATE(get_date) AS d,
SUBSTRING(get_date,12,2) as h
FROM t_env_sensor s where s.sensor_type=5 and s.mod_id=1 and date_format(s.get_date,'%Y-%m-%d')=date_format(now(),'%Y-%m-%d')
ORDER BY get_date DESC
) t_env_sensor
GROUP BY d,h