Counting number using numbers table with 15 minutes interval - sql

Question

What is the most efficient way to count the number of occurrences according?
I found the numbers table is the most efficient way to generate time sequence data based on start time and end time.
I have create a number table starts from 0 to 100,000.
I have generate time sequence table as following:
Declare #Start datetime = '2018-01-01 00:00:00.000',#End datetime ='2018-02-01 00:00:00.000';
SELECT
DATEADD(MINUTE,Number*15,#Start) StartTime,
[Number],
DATEADD(MINUTE,(Number+1)*15,#Start) EndTime
FROM dbo.Numbers
Where (Number+1)*15<=DATEDIFF(MINUTE,#Start,#End)
Order By Number;
I have table of data like:
Time ID
2018-01-01 00:00:01.000 1
2018-01-01 00:00:02.000 1
2018-01-01 00:15:00.000 124
2018-01-01 00:28:00.000 341
2018-01-01 00:26:00.000 111
2018-01-01 01:02:00.000 162
2018-01-01 04:09:00.000 110
2018-01-01 05:09:00.152 398
2018-01-01 08:12:00.000 902
2018-01-01 12:45:00.000 009
2018-01-01 13:23:00.000 000
2018-01-01 15:37:00.000 187
How can I count time based on 15 minutes interval?

Answer 1

You can try to use cte recursive to make a calendar table then do outer join
Declare #Start datetime = '2018-01-01 00:00:00.000',#End datetime ='2018-02-01 00:00:00.000';
;WITH CTE AS (
SELECT #Start startTime,DATEADD(MINUTE,15,#Start) nextTime,#End endTime
UNION ALL
SELECT DATEADD(MINUTE,15,startTime),DATEADD(MINUTE,15,nextTime) nextTime,#End
FROM CTE
WHERE DATEADD(MINUTE,15,startTime) < #End
)
SELECT startTime,nextTime,COUNT(t1.ID)
FROM CTE c1
LEFT JOIN T t1 on t1.Time BETWEEN c1.startTime and c1.nextTime
GROUP BY startTime,nextTime
option ( MaxRecursion 0 );
Note
The CTE default maximum recursion is 100, you can sett option ( MaxRecursion 0 );
The statement terminated. The maximum recursion 100 has been exhausted before statement completion.
Sqlfiddle

Answer 2

How about this. Just a normal group by so you can put in HAVING, SUM, AVERAGE etc too if you want. Run top section once:
create table TestTable
(
Time datetime,
ID int
)
GO
insert into TestTable values('2018-01-01 00:00:01.000' , 1)
insert into TestTable values('2018-01-01 00:00:02.000' , 1)
insert into TestTable values('2018-01-01 00:15:00.000' ,124)
insert into TestTable values('2018-01-01 00:28:00.000' ,341)
insert into TestTable values('2018-01-01 00:26:00.000' ,111)
insert into TestTable values('2018-01-01 01:02:00.000' ,162)
GO
CREATE FUNCTION [dbo].[RoundTime] (#Time datetime, #RoundTo float) RETURNS datetime
AS
BEGIN
DECLARE #RoundedTime smalldatetime, #Multiplier float
SET #Multiplier = 24.0 / #RoundTo
SET #RoundedTime= ROUND(CAST(CAST(CONVERT(varchar, #Time, 121) AS datetime) AS float) * #Multiplier, 0) / #Multiplier
RETURN #RoundedTime
END
GO
Then the actual working:
DECLARE #startDate DATETime
DECLARE #endDate DATETime
SET #startDate = '2018-01-01'
SET #endDate = GETDATE()
DECLARE #dateAxis TABLE
(
dt DATETime
)
DECLARE #currentDate DATETime = #startDate
WHILE #currentDate <= #endDate
BEGIN
INSERT INTO #dateAxis
SELECT #currentDate
SET #currentDate = DATEADD(Minute, 15, #currentDate)
END
-- axis table
--select * from #dateAxis
SELECT
dt AS joinDt,
dataset.MyCount
FROM
#dateAxis axis
LEFT JOIN
(
SELECT
dbo.RoundTime([Time], 0.5) AS joinDt,
count(*) AS MyCount
FROM
/*Your table here*/
TestTable tt
group by
dbo.RoundTime([Time], 0.5)
) dataset
ON dataset.joinDt = axis.dt
ORDER BY
axis.dt