I have a table (distance_travelled) with the columns
Primary Key | VehicleName | StartDate | Enddate | Total Distance
another table called Idling with columns
Vehicle Name | Duration | Timestamp
I have taken steps to get far but best way to ask the question is from scratch
i want the output to be the following table with columns
VehicleName | StartDate | EndDate | TotalDistance | Duration (sum of durations between each startDate and enddate
A CROSS APPLY may be a good fit here.
However, I get 18:15 for ID 2 (the sum of 8:15 and 10:00). Perhaps a typo/error in the original question, or additional logic is required.
I should note that the hours CAN exceed 24 just in case it spans multiple days.
Select A.*
,Duration = Format(IsNull(B.Seconds,0)/3600 ,'00') -- Hours 00 - 99
+Format(IsNull(B.Seconds,0)%3600/60,':00') -- Minutes
--+Format(IsNull(B.Seconds,0)%60 ,':00') -- Seconds
From Distance_Travelled A
Cross Apply (
Select Seconds = sum(DateDiff(SECOND,'1900-01-01',Duration))
From Idling
Where VehicleName = A.VehicleName
and TimeStamp between A.StartDate and A.EndDate
) B
Returns
Kind of nasty but you get the idea:
select
dt.id,
dt.VehicleName,
dt.StartDate,
dt.EndDate,
dt.Total_Distance,
substring(cast(convert(time,dateadd(millisecond,sum(datediff(millisecond,0,cast([Duration] as datetime))),0),108) as varchar),0,9) [Duration],
case when substring(cast(convert(time,dateadd(millisecond,sum(datediff(millisecond,0,cast([Duration] as datetime))),0),108) as varchar),0,9) is null then
'no duration...'
else
'sum between ' + convert(varchar, dt.StartDate, 108) + ' and ' + convert(varchar, dt.EndDate, 108)
end as [Duration]
from
distance_travelled dt
left join idling i on
dt.vehiclename = i.VehicleName and
i.TimeStamp between dt.StartDate and dt.EndDate
group by
dt.id,
dt.VehicleName,
dt.StartDate,
dt.EndDate,
dt.Total_Distance
Related
There's a table with three columns: start date, end date and task duration in hours. For example, something like that:
Id
StartDate
EndDate
Duration
1
07-11-2022
15-11-2022
40
2
02-09-2022
02-11-2022
122
3
10-10-2022
05-11-2022
52
And I want to get a table like that:
Id
Month
HoursPerMonth
1
11
40
2
09
56
2
10
62
2
11
4
3
10
42
3
11
10
Briefly, I wanted to know, how many working hours is in each month between start and end dates. Proportionally. How can I achieve that by MS SQL Query? Data is quite big so the query speed is important enough. Thanks in advance!
I've tried DATEDIFF and EOMONTH, but that solution doesn't work with tasks > 2 months. And I'm sure that this solution is bad decision. I hope, that it can be done more elegant way.
Here is an option using an ad-hoc tally/calendar table
Not sure I'm agree with your desired results
Select ID
,Month = month(D)
,HoursPerMonth = (sum(1.0) / (1+max(datediff(DAY,StartDate,EndDate)))) * max(Duration)
From YourTable A
Join (
Select Top 75000 D=dateadd(day,Row_Number() Over (Order By (Select NULL)),0)
From master..spt_values n1, master..spt_values n2
) B on D between StartDate and EndDate
Group By ID,month(D)
Order by ID,Month
Results
This answer uses CTE recursion.
This part just sets up a temp table with the OP's example data.
DECLARE #source
TABLE (
SOURCE_ID INT
,STARTDATE DATE
,ENDDATE DATE
,DURATION INT
)
;
INSERT
INTO
#source
VALUES
(1, '20221107', '20221115', 40 )
,(2, '20220902', '20221102', 122 )
,(3, '20221010', '20221105', 52 )
;
This part is the query based on the above data. The recursive CTE breaks the time period into months. The second CTE does the math. The final selection does some more math and presents the results the way you want to seem them.
WITH CTE AS (
SELECT
SRC.SOURCE_ID
,SRC.STARTDATE
,SRC.ENDDATE
,SRC.STARTDATE AS 'INTERIM_START_DATE'
,CASE WHEN EOMONTH(SRC.STARTDATE) < SRC.ENDDATE
THEN EOMONTH(SRC.STARTDATE)
ELSE SRC.ENDDATE
END AS 'INTERIM_END_DATE'
,SRC.DURATION
FROM
#source SRC
UNION ALL
SELECT
CTE.SOURCE_ID
,CTE.STARTDATE
,CTE.ENDDATE
,CASE WHEN EOMONTH(CTE.INTERIM_START_DATE) < CTE.ENDDATE
THEN DATEADD( DAY, 1, EOMONTH(CTE.INTERIM_START_DATE) )
ELSE CTE.STARTDATE
END
,CASE WHEN EOMONTH(CTE.INTERIM_START_DATE, 1) < CTE.ENDDATE
THEN EOMONTH(CTE.INTERIM_START_DATE, 1)
ELSE CTE.ENDDATE
END
,CTE.DURATION
FROM
CTE
WHERE
CTE.INTERIM_END_DATE < CTE.ENDDATE
)
, CTE2 AS (
SELECT
CTE.SOURCE_ID
,CTE.STARTDATE
,CTE.ENDDATE
,CTE.INTERIM_START_DATE
,CTE.INTERIM_END_DATE
,CAST( DATEDIFF( DAY, CTE.INTERIM_START_DATE, CTE.INTERIM_END_DATE ) + 1 AS FLOAT ) AS 'MNTH_DAYS'
,CAST( DATEDIFF( DAY, CTE.STARTDATE, CTE.ENDDATE ) + 1 AS FLOAT ) AS 'TTL_DAYS'
,CAST( CTE.DURATION AS FLOAT ) AS 'DURATION'
FROM
CTE
)
SELECT
CTE2.SOURCE_ID AS 'Id'
,MONTH( CTE2.INTERIM_START_DATE ) AS 'Month'
,ROUND( CTE2.MNTH_DAYS/CTE2.TTL_DAYS * CTE2.DURATION, 0 ) AS 'HoursPerMonth'
FROM
CTE2
ORDER BY
CTE2.SOURCE_ID
,CTE2.INTERIM_END_DATE
;
My results agree with Mr. Cappelletti's, not the OP's. Perhaps some tweaking regarding the definition of a "Day" is needed. I don't know.
If time between start and end date is large (more than 100 months) you may want to specify OPTION (MAXRECURSION 0) at the end.
My query is as follows
SELECT
LEFT(TimePeriod,6) Period, -- string field with YYYYMMDD
SUM(Value) Value
FROM
f_Trans_GL
WHERE
Account = 228
GROUP BY
TimePeriod
And it returns
Period Value
---------------
201412 80
201501 20
201502 30
201506 50
201509 100
201509 100
I'd like to know the Value difference between rows where the period is 1 month apart. The calculation being [value period] - [value period-1].
The desired output being;
Period Value Calculated
-----------------------------------
201412 80 80 - null = 80
201501 20 20 - 80 = -60
201502 30 30 - 20 = 10
201506 50 50 - null = 50
201509 100 (100 + 100) - null = 200
This illustrates a second challenge, as the period needs to be evaluated if the year changes (the difference between 201501 and 201412 is one month).
And the third challenge being a duplicate Period (201509), in which case the sum of that period needs to be evaluated.
Any indicators on where to begin, if this is possible, would be great!
Thanks in advance
===============================
After I accepted the answer, I tailored this a little to suit my needs, the end result is:
WITH cte
AS (SELECT
ISNULL(CAST(TransactionID AS nvarchar), '_nullTransactionId_') + ISNULL(Description, '_nullDescription_') + CAST(Account AS nvarchar) + Category + Currency + Entity + Scenario AS UID,
LEFT(TimePeriod, 6) Period,
SUM(Value1) Value1,
CAST(LEFT(TimePeriod, 6) + '01' AS date) ord_date
FROM MyTestTable
GROUP BY LEFT(TimePeriod, 6),
TransactionID,
Description,
Account,
Category,
Currency,
Entity,
Scenario,
TimePeriod)
SELECT
a.UID,
a.Period,
--a.Value1,
ISNULL(a.Value1, 0) - ISNULL(b.Value1, 0) Periodic
FROM cte a
LEFT JOIN cte b
ON a.ord_date = DATEADD(MONTH, 1, b.ord_date)
ORDER BY a.UID
I have to get the new value (Periodic) for each UID. This UID must be determined as done here because the PK on the table won't work.
But the issue is that this will return many more rows than I actually have to begin with in my table. If I don't add a GROUP BY and ORDER by UID (as done above), I can tell that the first result for each combination of UID and Period is actually correct, the subsequent rows for that combination, are not.
I'm not sure where to look for a solution, my guess is that the UID is the issue here, and that it will somehow iterate over the field... any direction appreciated.
As pointed by other, first mistake is in Group by you need to Left(timeperiod, 6) instead of timeperiod.
For remaining calculation try something like this
;WITH cte
AS (SELECT LEFT(timeperiod, 6) Period,
Sum(value) Value,
Cast(LEFT(timeperiod, 6) + '01' AS DATE) ord_date
FROM f_trans_gl
WHERE account = 228
GROUP BY LEFT(timeperiod, 6))
SELECT a.period,
a.value,
a.value - Isnull(b.value, 0)
FROM cte a
LEFT JOIN cte b
ON a.ord_date = Dateadd(month, 1, b.ord_date)
If you are using SQL SERVER 2012 then this can be easily done using LAG analytic function
Using a derived table, you can join the data to itself to find rows that are in the preceding period. I have converted your Period to a Date value so you can use SQL Server's dateadd function to check for rows in the previous month:
;WITH cte AS
(
SELECT
LEFT(TimePeriod,6) Period, -- string field with YYYYMMDD
CAST(TimePeriod + '01' AS DATE) PeriodDate
SUM(Value) Value
FROM f_Trans_GL
WHERE Account = 228
GROUP BY LEFT(TimePeriod,6)
)
SELECT c1.Period,
c1.Value,
c1.Value - ISNULL(c2.Value,0) AS Calculation
FROM cte c1
LEFT JOIN cte c2
ON c1.PeriodDate = DATEADD(m,1,c2.PeriodDate)
Without cte, you can also try something like this
SELECT A.Period,A.Value,A.Value-ISNULL(B.Value) Calculated
FROM
(
SELECT LEFT(TimePeriod,6) Period
DATEADD(M,-1,(CONVERT(date,LEFT(TimePeriod,6)+'01'))) PeriodDatePrev,SUM(Value) Value
FROM f_Trans_GL
WHERE Account = 228
GROUP BY LEFT(TimePeriod,6)
) AS A
LEFT OUTER JOIN
(
SELECT LEFT(TimePeriod,6) Period
(CONVERT(date,LEFT(TimePeriod,6)+'01')) PeriodDate,SUM(Value) Value
FROM f_Trans_GL
WHERE Account = 228
GROUP BY LEFT(TimePeriod,6)
) AS B
ON (A.PeriodDatePrev = B.PeriodDate)
ORDER BY 1
I'm creating a report in a SQL Server database. I will show it's code first and then describe what it does and where is problem.
SELECT
COUNT(e.flowid) AS [count],
t.name AS [process],
CAST(DATEPART(YEAR, e.dtcr) AS VARCHAR) + '-' + CAST(RIGHT('0' + RTRIM(DATEPART(MONTH, e.dtcr)), 2) AS VARCHAR) + '-' + CAST(RIGHT('0' + RTRIM(DATEPART(DAY, e.dtcr)), 2) AS VARCHAR) AS [day]
FROM
dbo.[Event] e
JOIN
dbo.Flow f ON e.flowid = f.id
JOIN
dbo.WorkOrder o ON f.workorderno = o.number
AND o.treenodeid IN (26067, 26152, 2469, 1815, 1913) -- only from requested processes
JOIN
dbo.TreeNode t ON o.treenodeid = t.id -- for process name in select statement
JOIN
dbo.Product p ON f.productid = p.id
AND p.materialid NOT IN (26094, 27262, 27515, 27264, 28192, 28195, 26090, 26092, 26093, 27065, 26969, 27471, 28351, 28353, 28356, 28976, 27486, 29345, 29346, 27069, 28653, 28654, 26735, 26745, 28686) -- exclude unwanted family codes
WHERE
e.pass = 1 -- only passed units
AND e.treenodeid IN (9036, 9037, 9038, 9039, 12594, 26330) -- only from requested events
AND e.dtcr BETWEEN '2015-12-01 00:00:00.000' AND '2016-05-31 23:59:59.999' -- only from requested time interval
GROUP BY
DATEPART(YEAR, e.dtcr), DATEPART(MONTH, e.dtcr), DATEPART(DAY, e.dtcr), t.name
ORDER BY
[day]
What query does is count units that passed specific events in a time periods (with some filters).
Important tables are:
Event - basically log for units passing specific events.
Product - list of units.
Output is something like this:
COUNT PROCESS DAY
71 Process-1 2015-12-01
1067 Process-2 2015-12-01
8 Process-3 2015-12-01
3 Process-4 2015-12-01
15 Process-1 2015-12-02
276 Process-2 2015-12-02
47 Process-3 2015-12-02
54 Process-4 2015-12-02
It does well but there is an issue. In some specific cases unit can pass same event several times and this query counts every such passing. I need to count every unit only once.
"Duplicated" records are in Event table. They have different dates and ids. Same for all records I need to count only once is flowid. Is there any simple way to achieve this?
Thank you for your time and answers!
To count each flowid only once, do count(distinct flowid), i.e.
SELECT
COUNT(distinct e.flowid) AS [count],
t.name AS [process],
CAST(DATEPART(YEAR, e.dtcr) AS VARCHAR) + '-' + CAST(RIGHT('0' + RTRIM(DATEPART(MONTH, e.dtcr)), 2) AS VARCHAR) + '-' + CAST(RIGHT('0' + RTRIM(DATEPART(DAY, e.dtcr)), 2) AS VARCHAR) AS [day]
FROM
...
It sounds like you need the first time that something passes the threshold. You can get the first time using row_number(). This can be tricky with the additional conditions on the query. This modification might work for you:
select sum(case when seqnum = 1 then 1 else 0 end) as cnt,
. . .
from (select e.*,
row_number() over (partition by eventid order by e.dtcr) as seqnum
from event e
where e.pass = 1 and -- only passed units
e.treenodeid IN (9036, 9037, 9038, 9039, 12594, 26330) and
e.dtcr >= '2015-12-01' AND e.dtcr < '2016-06-01'
) e join
. . .
You don't specify how the same event is identified for the duplicates. The above uses eventid for this purpose.
Long time stalker, first time poster (and SQL beginner). My question is similar to this one SQL to find time elapsed from multiple overlapping intervals, except I'm able to use CTE, UDFs etc and am looking for more detail.
On a piece of large scale equipment I have a record of all faults that arise. Faults can arise on different sub-components of the system, some may take it offline completely (complete outage = yes), while others do not (complete outage = no). Faults can overlap in time, and may not have end times if the fault has not yet been repaired.
Outage_ID StartDateTime EndDateTime CompleteOutage
1 07:00 3-Jul-13 08:55 3-Jul13 Yes
2 08:30 3-Jul-13 10:00 4-Jul13 No
3 12:00 4-Jul-13 No
4 12:30 4-Jul13 12:35 4-Jul-13 No
1 |---------|
2 |---------|
3 |--------------------------------------------------------------
4 |---|
I need to be able to work out for a user defined time period, how long the total system is fully functional (no faults), how long its degraded (one or more non-complete outages) and how long inoperable (one or more complete outages). I also need to be able to work out for any given time period which faults were on the system. I was thinking of creating a "Stage Change" table anytime a fault is opened or closed, but I am stuck on the best way to do this - any help on this or better solutions would be appreciated!
This isn't a complete solution (I leave that as an exercise :)) but should illustrate the basic technique. The trick is to create a state table (as you say). If you record a 1 for a "start" event and a -1 for an "end" event then a running total in event date/time order gives you the current state at that particular event date/time. The SQL below is T-SQL but should be easily adaptable to whatever database server you're using.
Using your data for partial outage as an example:
DECLARE #Faults TABLE (
StartDateTime DATETIME NOT NULL,
EndDateTime DATETIME NULL
)
INSERT INTO #Faults (StartDateTime, EndDateTime)
SELECT '2013-07-03 08:30', '2013-07-04 10:00'
UNION ALL SELECT '2013-07-04 12:00', NULL
UNION ALL SELECT '2013-07-04 12:30', '2013-07-04 12:35'
-- "Unpivot" the events and assign 1 to a start and -1 to an end
;WITH FaultEvents AS (
SELECT *, Ord = ROW_NUMBER() OVER(ORDER BY EventDateTime)
FROM (
SELECT EventDateTime = StartDateTime, Evt = 1
FROM #Faults
UNION ALL SELECT EndDateTime, Evt = -1
FROM #Faults
WHERE EndDateTime IS NOT NULL
) X
)
-- Running total of Evt gives the current state at each date/time point
, FaultEventStates AS (
SELECT A.Ord, A.EventDateTime, A.Evt, [State] = (SELECT SUM(B.Evt) FROM FaultEvents B WHERE B.Ord <= A.Ord)
FROM FaultEvents A
)
SELECT StartDateTime = S.EventDateTime, EndDateTime = F.EventDateTime
FROM FaultEventStates S
OUTER APPLY (
-- Find the nearest transition to the no-fault state
SELECT TOP 1 *
FROM FaultEventStates B
WHERE B.[State] = 0
AND B.Ord > S.Ord
ORDER BY B.Ord
) F
-- Restrict to start events transitioning from the no-fault state
WHERE S.Evt = 1 AND S.[State] = 1
If you are using SQL Server 2012 then you have the option to calculate the running total using a windowing function.
The below is a rough guide to getting this working. It will compare against an interval table of dates and an interval table of 15 mins. It will then sum the outage events (1 event per interval), but not sum a partial outage if there is a full outage.
You could use a more granular time interval if you needed, I choose 15 mins for speed of coding.
I already had a date interval table set up "CAL.t_Calendar" so you would need to create one of your own to run this code.
Please note, this does not represent actual code you should use. It is only intended as a demonstration and to point you in a possible direction...
EDIT I've just realised I have't accounted for the null end dates. The code will need amending to check for NULL endDates and use #EndDate or GETDATE() if #EndDate is in the future
--drop table ##Events
CREATE TABLE #Events (OUTAGE_ID INT IDENTITY(1,1) PRIMARY KEY
,StartDateTime datetime
,EndDateTime datetime
, completeOutage bit)
INSERT INTO #Events VALUES ('2013-07-03 07:00','2013-07-03 08:55',1),('2013-07-03 08:30','2013-07-04 10:00',0)
,('2013-07-04 12:00',NULL,0),('2013-07-04 12:30','2013-07-04 12:35',0)
--drop table #FiveMins
CREATE TABLE #FiveMins (ID int IDENTITY(1,1) PRIMARY KEY, TimeInterval Time)
DECLARE #Time INT = 0
WHILE #Time <= 1410 --number of 15 min intervals in day * 15
BEGIN
INSERT INTO #FiveMins SELECT DATEADD(MINUTE , #Time, '00:00')
SET #Time = #Time + 15
END
SELECT * from #FiveMins
DECLARE #StartDate DATETIME = '2013-07-03'
DECLARE #EndDate DATETIME = '2013-07-04 23:59:59.999'
SELECT SUM(FullOutage) * 15 as MinutesFullOutage
,SUM(PartialOutage) * 15 as MinutesPartialOutage
,SUM(NoOutage) * 15 as MinutesNoOutage
FROM
(
SELECT DateAnc.EventDateTime
, CASE WHEN COUNT(OU.OUTAGE_ID) > 0 THEN 1 ELSE 0 END AS FullOutage
, CASE WHEN COUNT(OU.OUTAGE_ID) = 0 AND COUNT(pOU.OUTAGE_ID) > 0 THEN 1 ELSE 0 END AS PartialOutage
, CASE WHEN COUNT(OU.OUTAGE_ID) > 0 OR COUNT(pOU.OUTAGE_ID) > 0 THEN 0 ELSE 1 END AS NoOutage
FROM
(
SELECT CAL.calDate + MI.TimeInterval AS EventDateTime
FROM CAL.t_Calendar CAL
CROSS JOIN #FiveMins MI
WHERE CAL.calDate BETWEEN #StartDate AND #EndDate
) DateAnc
LEFT JOIN #Events OU
ON DateAnc.EventDateTime BETWEEN OU.StartDateTime AND OU.EndDateTime
AND OU.completeOutage = 1
LEFT JOIN #Events pOU
ON DateAnc.EventDateTime BETWEEN pOU.StartDateTime AND pOU.EndDateTime
AND pOU.completeOutage = 0
GROUP BY DateAnc.EventDateTime
) AllOutages
For a development aid project I am helping a small town in Nicaragua improving their water-network-administration.
There are about 150 households and every month a person checks the meter and charges the houshold according to the consumed water (reading from this month minus reading from last month). Today all is done on paper and I would like to digitalize the administration to avoid calculation-errors.
I have an MS Access Table in mind - e.g.:
*HousholdID* *Date* *Meter*
0 1/1/2013 100
1 1/1/2013 130
0 1/2/2013 120
1 1/2/2013 140
...
From this data I would like to create a query that calculates the consumed water (the meter-difference of one household between two months)
*HouseholdID* *Date* *Consumption*
0 1/2/2013 20
1 1/2/2013 10
...
Please, how would I approach this problem?
This query returns every date with previous date, even if there are missing months:
SELECT TabPrev.*, Tab.Meter as PrevMeter, TabPrev.Meter-Tab.Meter as Diff
FROM (
SELECT
Tab.HousholdID,
Tab.Data,
Max(Tab_1.Data) AS PrevData,
Tab.Meter
FROM
Tab INNER JOIN Tab AS Tab_1 ON Tab.HousholdID = Tab_1.HousholdID
AND Tab.Data > Tab_1.Data
GROUP BY Tab.HousholdID, Tab.Data, Tab.Meter) As TabPrev
INNER JOIN Tab
ON TabPrev.HousholdID = Tab.HousholdID
AND TabPrev.PrevData=Tab.Data
Here's the result:
HousholdID Data PrevData Meter PrevMeter Diff
----------------------------------------------------------
0 01/02/2013 01/01/2013 120 100 20
1 01/02/2013 01/01/2012 140 130 10
The query above will return every delta, for every households, for every month (or for every interval). If you are just interested in the last delta, you could use this query:
SELECT
MaxTab.*,
TabCurr.Meter as CurrMeter,
TabPrev.Meter as PrevMeter,
TabCurr.Meter-TabPrev.Meter as Diff
FROM ((
SELECT
Tab.HousholdID,
Max(Tab.Data) AS CurrData,
Max(Tab_1.Data) AS PrevData
FROM
Tab INNER JOIN Tab AS Tab_1
ON Tab.HousholdID = Tab_1.HousholdID
AND Tab.Data > Tab_1.Data
GROUP BY Tab.HousholdID) As MaxTab
INNER JOIN Tab TabPrev
ON TabPrev.HousholdID = MaxTab.HousholdID
AND TabPrev.Data=MaxTab.PrevData)
INNER JOIN Tab TabCurr
ON TabCurr.HousholdID = MaxTab.HousholdID
AND TabCurr.Data=MaxTab.CurrData
and (depending on what you are after) you could only filter current month:
WHERE
DateSerial(Year(CurrData), Month(CurrData), 1)=
DateSerial(Year(DATE()), Month(DATE()), 1)
this way if you miss a check for a particular household, it won't show.
Or you might be interested in showing last month present in the table (which can be different than current month):
WHERE
DateSerial(Year(CurrData), Month(CurrData), 1)=
(SELECT MAX(DateSerial(Year(Data), Month(Data), 1))
FROM Tab)
(here I am taking in consideration the fact that checks might be on different days)
I think the best approach is to use a correlated subquery to get the previous date and join back to the original table. This ensures that you get the previous record, even if there is more or less than a 1 month lag.
So the right query looks like:
select t.*, tprev.date, tprev.meter
from (select t.*,
(select top 1 date from t t2 where t2.date < t.date order by date desc
) prevDate
from t
) join
t tprev
on tprev.date = t.prevdate
In an environment such as the one you describe, it is very important not to make assumptions about the frequency of reading the meter. Although they may be read on average once per month, there will always be exceptions.
Testing with the following data:
HousholdID Date Meter
0 01/12/2012 100
1 01/12/2012 130
0 01/01/2013 120
1 01/01/2013 140
0 01/02/2013 120
1 01/02/2013 140
The following query:
SELECT a.housholdid,
a.date,
b.date,
a.meter,
b.meter,
a.meter - b.meter AS Consumption
FROM (SELECT *
FROM water
WHERE Month([date]) = Month(Date())
AND Year([date])=year(Date())) a
LEFT JOIN (SELECT *
FROM water
WHERE DateSerial(Year([date]),Month([date]),Day([date]))
=DateSerial(Year(Date()),Month(Date())-1,Day([date])) ) b
ON a.housholdid = b.housholdid
The above query selects the records for this month Month([date]) = Month(Date()) and compares them to records for last month ([date]) = Month(Date()) - 1)
Please do not use Date as a field name.
Returns the following result.
housholdid a.date b.date a.meter b.meter Consumption
0 01/02/2013 01/01/2013 120 100 20
1 01/02/2013 01/01/2013 140 130 10
Try
select t.householdID
, max(s.theDate) as billingMonth
, max(s.meter)-max(t.meter) as waterUsed
from myTbl t join (
select householdID, max(theDate) as theDate, max(meter) as meter
from myTbl
group by householdID ) s
on t.householdID = s.householdID and t.theDate <> s.theDate
group by t.householdID
This works in SQL not sure about access
You can use the LAG() function in certain SQL dialects. I found this to be much faster and easier to read than joins.
Source: http://blog.jooq.org/2015/05/12/use-this-neat-window-function-trick-to-calculate-time-differences-in-a-time-series/