SQL Server : Gap / Island, datetime, contiguous block 365 day block - sql

Question

I have a table that looks like this:-
tblMeterReadings
id meter period_start period_end amount
1 1 2014-01-01 00:00 2014-01-01 00:29:59 100.3
2 1 2014-01-01 00:30 2014-01-01 00:59:59 50.5
3 1 2014-01-01 01:00 2014-01-01 01:29:59 70.7
4 1 2014-01-01 01:30 2014-01-01 01:59:59 900.1
5 1 2014-01-01 02:00 2014-01-01 02:29:59 400.0
6 1 2014-01-01 02:30 2014-01-01 02:59:59 200.3
7 1 2014-01-01 03:00 2014-01-01 03:29:59 100.8
8 1 2014-01-01 03:30 2014-01-01 03:59:59 140.3
This is a tiny "contiguous block" from '2014-01-01 00:00' to '2014-01-01 3:59:59'.
In the real table there are "contiguous blocks" of years in length.
I need to find the the period_start and period_end of the most recent CONTINUOUS 365 COMPLETE DAYs (fileterd by meter column).
When I say COMPLETE DAYs I mean a day that has entries spanning 00:00 to 23:59.
When I say CONTINUOUS I mean there must be no days missing.
I would like to select all the rows that make up this block of CONTINUOUS COMPLETE DAYs.
I also need an output like:
block_start block_end total_amount_for_block
2013-02-26 00:00 2014-02-26 23:59:59 1034234.5
This is beyond me, so if someone can solve... I will be very impressed.

Answer 1

Since your granularity is 1 second, you need to expand your periods into all the date/times between the start and end at 1 second intervals. To do this you need to cross join with a numbers table (The numbers table is generated on the fly by ranking object ids from an arbitrary system view, I have limited it to TOP 86400 since this is the number of seconds in a day, and you have stated your time periods never span more than one day):
WITH Numbers AS
( SELECT TOP (86400)
Number = ROW_NUMBER() OVER(ORDER BY a.object_id) - 1
FROM sys.all_objects a
CROSS JOIN sys.all_objects b
ORDER BY a.object_id
)
SELECT r.ID, r.meter, dt.[DateTime]
FROM tblMeterReadings r
CROSS JOIN Numbers n
OUTER APPLY
( SELECT [DateTime] = DATEADD(SECOND, n.Number, r.period_start)
) dt
WHERE dt.[DateTime] <= r.Period_End;
You then have your continuous range in which to perform the normal gaps and islands grouping:
WITH Numbers AS
( SELECT TOP (86400)
Number = ROW_NUMBER() OVER(ORDER BY a.object_id) - 1
FROM sys.all_objects a
CROSS JOIN sys.all_objects b
ORDER BY a.object_id
), Grouped AS
( SELECT r.meter,
Amount = CASE WHEN Number = 1 THEN r.Amount ELSE 0 END,
dt.[DateTime],
GroupingSet = DATEADD(SECOND,
-DENSE_RANK() OVER(PARTITION BY r.Meter
ORDER BY dt.[DateTime]),
dt.[DateTime])
FROM tblMeterReadings r
CROSS JOIN Numbers n
OUTER APPLY
( SELECT [DateTime] = DATEADD(SECOND, n.Number, r.period_start)
) dt
WHERE dt.[DateTime] <= r.Period_End
)
SELECT meter,
PeriodStart = MIN([DateTime]),
PeriodEnd = MAX([DateTime]),
Amount = SUM(Amount)
FROM Grouped
GROUP BY meter, GroupingSet
HAVING DATEADD(YEAR, 1, MIN([DateTime])) < MAX([DateTime]);
N.B. Since the join to Number causes amounts to be duplicated, it is necessary to set all duplicates to 0 using CASE WHEN Number = 1 THEN r.Amount ELSE 0 END, i.e only include the amount for the first row for each ID
Removing the Having clause for your sample data will give:
meter | PeriodStart | PeriodEnd | Amount
------+---------------------+---------------------+----------
1 | 2014-01-01 00:00:00 | 2014-01-01 03:59:59 | 1963
Example on SQL Fiddle

Answer 2

You could try this:
Select MIN(period_start) as "block start"
, MAX(period_end) as "block end"
, SUM(amount) as "total amount"
FROM YourTable
GROUP BY datepart(year, period_start)
, datepart(month, period_start)
, datepart(day, period_start)
, datepart(year, period_end)
, datepart(month, period_end)
, datepart(day, period_end)
Having datepart(year, period_start) = datepart(year, period_end)
AND datepart(month, period_start) = datepart(month, period_end)
AND datepart(day, period_start) = datepart(day, period_end)
AND datepart(hour, MIN(period_start)) = 0
AND datepart(minute,MIN(period_start)) = 0
AND datepart(hour, MAX(period_end)) = 23
AND datepart(minute,MIN(period_end)) = 59