Calculate time duration with daily limits in SQL - sql

Question

I have a table that stores some events in the database, which log operational time of machines and I'd like to calculate a total running time within a specific date for a specific shift (or all shifts).
CREATE TABLE events (
ID int,
StartTime datetime,
EndTime datetime,
DurationSeconds bigint,
...
)
I'd like to select total duration of events in the specified date range #dateStart datetime, #dateEnd datetime while considering daily shifts (#shiftStart time, #shiftEnd time). The events will overlap the shifts and the date ranges.
For example, if I have shift starting at 6:00 and ending at 12:00, and the event lasted for whole 2 days (2014/01/01 00:00 - 2014/01/03 00:00), the total time for this row is (48 hours - 2*6 hours = 36 hours).
If an event starts in the middle of the shift, then only the 'in-shift' portion should be considered.
So far I had an implementation without considering the shifts like:
select sum(
--duration minus start overlap and end overlap
duration - dbo.udf_max(datediff(s,#pTo,endtime),0) - dbo.udf_max(datediff(s,starttime,#pFrom),0)
)
from events
where starttime < #pTo and endtime > #pFrom
I'd really like to have a set-based solution as the data sets are rather large and consider a looping cursor-based solution as the last resort.

Answer 1

Ok lets make some test data (I changed the times a little to show variance)
DECLARE #Events TABLE
(
ID int IDENTITY (1, 1),
StartTime datetime,
EndTime datetime,
DurationSeconds bigint
)
INSERT INTO #Events
( StartTime, EndTime )
VALUES
( '2014/01/01 01:00', '2014/01/02 22:00');
DECLARE #Shift TABLE
(
ShiftName VARCHAR(20),
StartTime DATETIME,
EndTime DATETIME
)
INSERT INTO #Shift
( ShiftName, StartTime, EndTime )
VALUES
( 'Night', '2014/01/01 00:00', '2014/01/01 06:00' ),
( 'Morning', '2014/01/01 06:00', '2014/01/01 12:00' ),
( 'Afternoon', '2014/01/01 12:00', '2014/01/01 18:00' ),
( 'Evening', '2014/01/01 18:00', '2014/01/02 00:00' ),
( 'Night', '2014/01/02 00:00', '2014/01/02 06:00' ),
( 'Morning', '2014/01/02 06:00', '2014/01/02 12:00' ),
( 'Afternoon', '2014/01/02 12:00', '2014/01/02 18:00' ),
( 'Evening', '2014/01/02 18:00', '2014/01/03 00:00' );
Here I make a numbers table to find all the minutes for the events duration
DECLARE #StartDate DATETIME = '1/1/2014';
DECLARE #number_of_numbers INT = 100000;
;WITH
a AS (SELECT 1 AS i UNION ALL SELECT 1),
b AS (SELECT 1 AS i FROM a AS x, a AS y),
c AS (SELECT 1 AS i FROM b AS x, b AS y),
d AS (SELECT 1 AS i FROM c AS x, c AS y),
e AS (SELECT 1 AS i FROM d AS x, d AS y),
f AS (SELECT 1 AS i FROM e AS x, e AS y),
numbers AS
(
SELECT TOP(#number_of_numbers)
ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) AS number
FROM f
), mins_in_day AS
Now I find all the minutes worked for each shift and total them
(
SELECT DATEADD(MINUTE, n.number, #StartDate) AS DayMinute
FROM numbers n
), output AS
(
SELECT s.ShiftName, CONVERT(DATE, s.StartTime) ShiftDay, COUNT(1) AS TotalMinutes FROM #Shift s
INNER JOIN mins_in_day sc
ON sc.DayMinute >= s.StartTime AND sc.DayMinute < s.EndTime
INNER JOIN #Events e
ON sc.DayMinute >= e.StartTime AND sc.DayMinute <e.EndTime
GROUP BY s.ShiftName, s.StartTime
)
SELECT * FROM output
Here is the output:
ShiftName ShiftDay TotalMinutes
Night 2014-01-01 300
Morning 2014-01-01 360
Afternoon 2014-01-01 360
Evening 2014-01-01 360
Night 2014-01-02 360
Morning 2014-01-02 360
Afternoon 2014-01-02 360
Evening 2014-01-02 240