I have few records and i want to create a query to give hourly records of a each divece battery level
What i did from timestamp field i extract date and select min function to get low value but as extract hour from timestamp is not aggragate function so i need to add in group by which now given me duplicate records.
Here is my sql:
select extract(hour from observationtime) as hour,
deviceid,
min(batterylevel) as batterylevel
from smartvakt_device_report
where batterylevel!=''
and deviceid!=''
and observationtime between '2016-02-02' and '2016-03-02'
group by observationtime,deviceid
order by observationtime ASC, deviceid ASC
Here is above query output:
Here are actual records:
Can someone suggest how i can remove these duplicate
Change Group by column Order to first Group by deviceid then by the hour using the same function extract(hour from observationtime).
SELECT
deviceid,
extract(hour from observationtime) AS hour,
min(batterylevel) AS batterylevel
FROM smartvakt_device_report
WHERE
batterylevel!=''
AND deviceid!=''
AND observationtime BETWEEN '2016-02-02'
AND '2016-03-02'
GROUP BY
deviceid,
extract(hour from observationtime)
ORDER BY
extract(hour from observationtime) ASC,
deviceid ASC
Since you are only interested in the hour, when you are grouping, you have to indicate that like this
group by extract(hour from observationtime)
Otherwise, postgresql will try to group together rows whose observationtime values are identical. But observationtime contains the time with full resolution, not just the hour.
Related
hi i'm trying to group the data by hour in big
so how can I group the data by the hour to count the orders per hour?
Use below
select date,
extract(hour from parse_time('%I:%M:%S %p', time)) as hour,
count(distinct order_id) as orders
from your_table
group by date, hour
if applied to sample data in your question - output is
I've got a SQL query that selects every data between two dates and now I would like to add the time scale factor so that instead of returning all the data it returns one data every second, minute or hour.
Do you know how I can achieve it ?
My query :
"SELECT received_on, $1 FROM $2 WHERE $3 <= received_on AND received_on <= $4", [data_selected, table_name, date_1, date_2]
The table input:
As you can see there are several data the same second, I would like to select only one per second
If you want to select data every second, you may use ROW_NUMBER() function partitioned by 'received_on' as the following:
WITH DateGroups AS
(
SELECT *, ROW_NUMBER() OVER (PARTITION BY received_on ORDER BY adc_v) AS rn
FROM table_name
)
SELECT received_on, adc_v, adc_i, acc_axe_x, acc_axe_y, acc_axe_z
FROM DateGroups
WHERE rn=1
ORDER BY received_on
If you want to select data every minute or hour, you may use the extract function to get the number of seconds in 'received_on' and divide it by 60 to get the minutes or divide it by 3600 to get the hours.
epoch: For date and timestamp values, the number of seconds since 1970-01-01 00:00:00-00 (can be negative); for interval values, the total number of seconds in the interval
Group by minutes:
WITH DateGroups AS
(
SELECT *, ROW_NUMBER() OVER (PARTITION BY floor(extract(epoch from (received_on)) / 60) ORDER BY adc_v) AS rn
FROM table_name
)
SELECT received_on, adc_v, adc_i, acc_axe_x, acc_axe_y, acc_axe_z
FROM DateGroups
WHERE rn=1
ORDER BY received_on
Group by hours:
WITH DateGroups AS
(
SELECT *, ROW_NUMBER() OVER (PARTITION BY floor(extract(epoch from (received_on)) / (60*60)) ORDER BY adc_v) AS rn
FROM table_name
)
SELECT received_on, adc_v, adc_i, acc_axe_x, acc_axe_y, acc_axe_z
FROM DateGroups
WHERE rn=1
ORDER BY received_on
See a demo.
When there are several rows per second, and you only want one result row per second, you can decide to pick one of the rows for each second. This can be a randomly chosen row or you pick the row with the greatest or least value in a column as shown in Ahmed's answer.
It would be more typical, though, to aggregate your data per second. The columns show figures and you are interested in those figures. Your sample data shows two times the value 2509 and three times the value 2510 for the adc_v column at 2022-07-29, 15:52. Consider what you would like to see. Maybe you don't want this value go below some boundary, so you show the minimum value MIN(adc_v) to see how low it went in the second. Or you want to see the value that occured most often in the second MODE(adc_v). Or you'd like to see the average value AVG(adc_v). Make this decision for every value, so as to get the informarion most vital to you.
select
received_on,
min(adc_v),
avg(adc_i),
...
from mytable
group by received_on
order by received_on;
If you want this for another interval, say an hour instead of the month, truncate your received_on column accordingly. E.g.:
select
date_trunc('hour', received_on) as received_hour,
min(adc_v),
avg(adc_i),
...
from mytable
group by date_trunc('hour', received_on)
order by date_trunc('hour', received_on);
When I ask this question, I get multiple hits on divcode because there are different timestamps in pickdate. Is there a way to get the question to summarize the date so I get 1 value per division?
/*
Söker Vikt och volym Snitt
*/
select TO_CHAR(ROUND(O08T1.pickdate),'YYYY-MM-DD') as date_1,
O08T1.divcode,
sum(O08T1.calcwght) as Vikt, sum(O08T1.calcvol) as Volym,
count(*) as AntalOrder,
avg(O08T1.calcwght) as avg_vikt,
avg(O08T1.calcvol) as avg_Vol
from O08T1
where O08T1.pickdate >= #('Från datum',#DATE)
group by O08T1.pickdate, O08T1.divcode
order by Pickdate DESC
If you want the values grouped by day then don't use GROUP BY pickdate as that will group by each instant and have values down to an accuracy of a second. Instead, GROUP BY TRUNC(pickdate) which will truncate values to the start of the day and will aggregate all values on the same day together (and then, also, use TRUNC in the first line and in the ORDER BY):
select TO_CHAR(TRUNC(pickdate),'YYYY-MM-DD') as date_1,
divcode,
sum(calcwght) as Vikt,
sum(calcvol) as Volym,
count(*) as AntalOrder,
avg(calcwght) as avg_vikt,
avg(calcvol) as avg_Vol
from O08T1
where pickdate >= #('Från datum',#DATE)
group by TRUNC(pickdate),
divcode
order by TRUNC(pickdate) DESC
I have the following situation:
ID DATE_TIME AMOUNT
23 14-MAY-2021 10:47:01 5
23 14-MAY-2021 11:49:52 3
23 14-MAY-2021 12:03:18 4
How can get the sum of the amount and take the DATE by day not hourly?
Example:
ID DATE_TIME TOTAL
23 20210514 12
I tried this way but i got error:
SELECT DISTINCT ID, TO_CHAR(DATE_TIME, 'YYYYMMDD'), SUM(AMOUNT) AS TOTAL FROM MY_TABLE
WHERE ID ='23' AND DATE_TIME > SYSDATE-1
GROUP BY TOTAL, DATE_TIME
You don't need DISTINCT if you use GROUP BY - anything that is grouped must be distinct unless it joined to something else later on that caused it to repeat again
You were almost there too
SELECT ID, TO_CHAR(DATE_TIME, 'YYYYMMDD') AS DATE_TIME, SUM(AMOUNT) AS TOTAL
FROM MY_TABLE
WHERE ID ='23' AND DATE_TIME > SYSDATE-1
GROUP BY ID, TO_CHAR(DATE_TIME, 'YYYYMMDD')
You need to group by the output of the function, not the input. Not every database can GROUP BY aliases used in the select (technically the SELECT hasn't been done by the time the GROUP is done so the aliases don't exist yet, and you wouldnt group by the total because that's an aggregate (the result of summing up every various value in the group)
If you need to do further work with that date, don't convert it to a string.. Cut the time off using TRUNC:
SELECT ID, TRUNC(DATE_TIME) as DATE_TIME, SUM(AMOUNT) AS TOTAL
FROM MY_TABLE
WHERE ID ='23' AND DATE_TIME > SYSDATE-1
GROUP BY ID, TRUNC(DATE_TIME)
TRUNC can cut a date down to other parts, for example TRUNC(DATE_TIME, 'HH24') will remove the minutes and seconds but leave the hours
Convert the DATE column to a string with the required accuracy and then group on that:
SELECT ID,
TO_CHAR("DATE", 'YYYY-MM-DD'),
SUM(AMOUNT) AS TOTAL FROM MY_TABLE
WHERE ID ='23'
AND "DATE" > SYSDATE-1
GROUP BY ID, TO_CHAR("DATE", 'YYYY-MM-DD')
or truncate the value so that the time component is set to midnight for each date:
SELECT ID,
TRUNC("DATE"),
SUM(AMOUNT) AS TOTAL FROM MY_TABLE
WHERE ID ='23'
AND "DATE" > SYSDATE-1
GROUP BY ID, TRUNC("DATE")
(Note: DATE is a keyword and cannot be used as an identifier unless you use a quoted-identifier; and you would need to use the quotes, and the exact case, everytime you refer to the column. You would be better to rename the column to something else that is not a keyword.)
I have a table "meterreading" that has columns: "timestamp", "value", "meterId". I would like to get sums of the "value" for each hour starting a specific time... So far I have come up with this query, but it is erroring saying I need to group by timestamp. Timestamps are just integers representing unix epoch timestamps.
select date_trunc('hour', to_timestamp(timestamp)) as hours, sum(value)
from meterreading
WHERE timestamp >= 1377993600 AND timestamp < 1409595081
group by date_trunc('hours', to_timestamp(timestamp))
order by date_trunc('hours', to_timestamp(timestamp)) asc
select date_trunc('hour', to_timestamp(timestamp)) as hours, sum(value)
from meterreading
WHERE timestamp >= 1377993600 AND timestamp < 1409595081
group by 1
order by 1
or use the exact same expression used in the select list
group by date_trunc('hour', to_timestamp(timestamp));
Notice 'hour' in instead of 'hours'. Hence the convenience of the number reference syntax in the group by. It is clearer and less prone to errors.