I have a table that stores a sensor temperature readings every few seconds
Sample data looks like this
nId nOperationId strDeviceIp nIfIndex nValue nTimestamp
97 2 192.168.99.252 1 26502328 1593828551
158 2 192.168.99.252 1 26501704 1593828667
256 2 192.168.99.252 1 26501860 1593828788
354 2 192.168.99.250 1 26501704 1593828908
452 2 192.168.99.250 1 26501692 1593829029
I want to have the average temperature per device so I ran the following query
select strDeviceIp, AVG(CAST(nValue as bigint)) as val1
from myTable
where nOperationId = 2 and nTimestamp >= 1593828600 and nTimestamp <= 1593838600
group by strSwitchIp;
Where I can pass the time range I want.
My issue is that this gives me total average but I want steps or range I want to achieve that instead of one line I’ll get all the values in a range/step of say 5 minutes as a row.
P.S. I’m trying to show a graph.
Running the following query I get
strSwitchIp average
192.168.99.252 26501731
But I would like to get
strSwitchIp average timestamp
192.168.99.252 26201731 1593828600
192.168.99.252 26532731 1593828900
192.168.99.252 24501721 1593829200
192.168.99.252 26506531 1593829500
In this example I would like to get a row every 300 seconds, per device.
Advertisement
Answer
Since your nTimestamp
is number of seconds, you can simply add it to the GROUP BY
. Division by 300 gives you 300 second (5 minute) intervals. In SQL Server /
is integer division, which discards the fractional part.
select
strSwitchIp
,AVG(CAST(nValue as bigint)) as val1
,(nTimestamp / 300) * 300 AS Timestamp
from myTable
where
nOperationId = 2 and nTimestamp >= 1593828600 and nTimestamp <= 1593838600
group by
strSwitchIp
,nTimestamp / 300
;
nTimestamp / 300
gives an integer, a number of 5-minute intervals since 1970. /
discards here the fractional part.
When this number is multiplied back by 300, it becomes again the number of seconds since 1970, but “rounded” to the nearest 5-minute interval. Just as you showed in the question in the expected result.
For example:
1593828667 / 300 = 5312762.2233333333333333333333333
discard fractional part
1593828667 / 300 = 5312762
5312762 * 300 = 1593828600
So, all timestamps between 1593828600 and 1593828899 become 1593828600 and all values for these timestamps are grouped into one row and averaged.