I am trying to create a graph which shows power consumption for every hour within a day. My device sends data every 15 min to my server, and previous power_kwh is always equal or more than current value of power_kwh within sensor_id. In some cases I could have two or more power meters for one building, so I need to think about combining values with same periods.So I want to retrieve two rows for each hour with first and last value with in clause containing sensor_id values So I have table with values: date,power_kwh, sensor_id mytable
After searching internet for a while and I found query which is good but problems with sensor_id
SELECT
DATE,
power_kwh,
sensor_id
FROM
sensor_data
WHERE
(HOUR(DATE), MINUTE(DATE)) IN(
SELECT
HOUR(DATE),
MIN(MINUTE(DATE))
FROM
sensor_data
GROUP BY
HOUR(DATE)
)
UNION
SELECT
DATE,
power_kwh,
sensor_id
FROM
sensor_data
WHERE
(HOUR(DATE), MINUTE(DATE)) IN(
SELECT
HOUR(DATE),
MAX(MINUTE(DATE))
FROM
sensor_data
GROUP BY
HOUR(DATE)
);
My current result
+----------------------------+-----------+-----------+
| date | power_kwh | sensor_id |
+----------------------------+-----------+-----------+
| 2020-03-12 15:40:03.000000 | 682685.56 | 4 |
| 2020-03-12 15:59:03.000000 | 682688.44 | 5 |
| 2020-03-12 16:00:03.000000 | 682688.56 | 5 |
| 2020-03-12 16:59:06.000000 | 682697.44 | 5 |
| 2020-03-12 17:00:06.000000 | 682697.56 | 5 |
| 2020-03-12 17:59:08.000000 | 682706.44 | 5 |
| 2020-03-12 18:00:08.000000 | 682706.56 | 5 |
| 2020-03-12 18:59:11.000000 | 682715.44 | 5 |
| 2020-03-12 19:00:11.000000 | 682715.56 | 5 |
| 2020-03-12 19:59:13.000000 | 682724.44 | 5 |
| 2020-03-12 20:00:13.000000 | 682724.56 | 5 |
| 2020-03-12 20:59:16.000000 | 682733.44 | 5 |
My expected result
+----------------------------+-----------+-----------+
| date | power_kwh | sensor_id |
+----------------------------+-----------+-----------+
| 2020-03-12 15:40:03.000000 | 153566.34 | 4 |
| 2020-03-12 15:59:03.000000 | 153575.44 | 4 |
| 2020-03-12 15:00:02.000000 | 682688.56 | 5 |
| 2020-03-12 15:58:06.000000 | 682697.44 | 5 |
| 2020-03-12 16:00:06.000000 | 153576.23 | 4 |
| 2020-03-12 16:59:08.000000 | 153585.44 | 4 |
| 2020-03-12 16:02:08.000000 | 682706.56 | 5 |
| 2020-03-12 16:59:11.000000 | 682715.44 | 5 |
My sql version is
mysql Ver 8.0.19 for osx10.14 on x86_64 (Homebrew)
And one more thing, I thinking about speed and other stuff, so if there is no solution can you give me advice with processing it in a Java Spring Let me know if you guys need more information. Thank you!!!
If you are running MySQL 8.0, you can use window functions:
select date, power_kwh, sensor_id
from (
select
s.*,
row_number() over(partition by s.sensor_id, date(s.date), hour(s.date) order by s.date) rn_asc,
row_number() over(partition by s.sensor_id, date(s.date), hour(s.date) order by s.date desc) rn_desc
from sensor_data s
) t
where rn_asc = 1 or rn_desc = 1
In earlier versions, you can join with an aggregate query:
select s.date, s.power_kwh, s.sensor_id
from sensor_data s
inner join (
select sensor_id, min(date) min_date, max(date) max_date
from sensor_data
group by sensor_id, date(date), hour(date)
) g
on g.sensor_id = s.sensor_id
and s.date in (g.min_date, g.max_date)