SQL每小时​​数据

Question

The query below retrieves weather data from a MySql database, and groups this data in to an hourly format.

select hour(datetime) AS hour
     , avg(Temperature) as AVGT 
from Database.minute
WHERE DATETIME
      BETWEEN (CURDATE() + INTERVAL (SELECT hour(NOW())) hour - INTERVAL 23 hour)
         AND ((CURDATE() + INTERVAL (SELECT hour(NOW())) hour))
group by hour
order by  (CURDATE() + INTERVAL (SELECT hour(NOW())) hour - INTERVAL 23 hour)

Output is as follows:

hour    AVGT
19     11.730
20     11.970
21     11.970
22     11.760
23     11.660
0      11.700
1      11.830
2      12.370
3      12.770
4      12.840
5      12.840
6      12.540
7      12.500
8      12.030
9      12.100
10     12.300
11     12.060
12     11.090
13     10.920
14     10.920
15     10.820
16     10.760
17     10.690
18     10.560

The time is now 18:15. All of the above output is correct apart from the data gathered for hour '18'. Instead of getting the average value between 18:00 and 18:15, it just outputs the average at time 18:00. ie. ignoring data between 18:01 and 18:14.

How can I modify the above query to include data in the current hour (18:00 to Now)?

Thanks

Answer 1

Why don't you simply try

SELECT Hour(datetime)   AS hour, 
       Avg(temperature) AS AVGT 
FROM   DATABASE.minute 
WHERE  datetime BETWEEN ( Curdate() + INTERVAL (SELECT Hour(Now())) hour - 
                          INTERVAL 23 hour ) AND Now() 
GROUP  BY hour 
ORDER  BY ( Curdate() + INTERVAL (SELECT Hour(Now())) hour - INTERVAL 23 hour ) 

Answer 2

I agree with @Ankur's answer (your filter citerion should not filter records up to the current hour, but rather the current time), however your date/time operations are very strange:

1. You don't need a subquery (SELECT Hour(NOW())) to obtain HOUR(NOW()) ;

2. You can express ( Curdate() + INTERVAL (SELECT Hour(NOW())) hour - INTERVAL 23 hour ) more simply:

    CURDATE() + INTERVAL HOUR(NOW()) - 23 HOUR 

   Or, in my view, more clearly:

    DATE_FORMAT(NOW() - INTERVAL 23 HOUR, '%Y-%m-%d %H:00:00') 

3. Your ORDER BY clause is a constant and therefore achieves nothing: did you mean to order by hour ?

Therefore:

SELECT   HOUR(datetime) AS hour,
         AVG(Temperature) AS AVGT
FROM     Database.minute
WHERE    datetime BETWEEN
               DATE_FORMAT(NOW() - INTERVAL 23 HOUR, '%Y-%m-%d %H:00:00')
           AND NOW()
GROUP BY hour
ORDER BY hour