Calculating total time excluding overlapped time & breaks in SQLServer - sql

Question

From the list of start time and end times from a select query, I need to find out the total time excluding overlapping time and breaks.
StartTime EndTime
2014-10-01 10:30:00.000 2014-10-01 12:00:00.000 -- 90 mins
2014-10-01 10:40:00.000 2014-10-01 12:00:00.000 --0 since its overlapped with previous
2014-10-01 10:42:00.000 2014-10-01 12:20:00.000 -- 20 mins excluding overlapped time
2014-10-01 10:40:00.000 2014-10-01 13:00:00.000 -- 40 mins
2014-10-01 10:44:00.000 2014-10-01 12:21:00.000 -- 0 previous ones have already covered this time range
2014-10-13 15:50:00.000 2014-10-13 16:00:00.000 -- 10 mins
So the total should be 160 mins in this case.
I don't want to use so many loops to get through with this. Looking for some simple solution.

Answer 1

DECLARE #table TABLE (StartTime DateTime2, EndTime DateTime2)
INSERT INTO #table SELECT '2014-10-01 10:30:00.000', '2014-10-01 12:00:00.000'
INSERT INTO #table SELECT '2014-10-01 10:40:00.000', '2014-10-01 12:00:00.000'
INSERT INTO #table SELECT '2014-10-01 10:42:00.000', '2014-10-01 12:20:00.000'
INSERT INTO #table SELECT '2014-10-01 10:40:00.000', '2014-10-01 13:00:00.000'
INSERT INTO #table SELECT '2014-10-01 10:44:00.000', '2014-10-01 12:21:00.000'
INSERT INTO #table SELECT '2014-10-13 15:50:00.000', '2014-10-13 16:00:00.000'
;WITH addNR AS ( -- Add row numbers
SELECT StartTime, EndTime, ROW_NUMBER() OVER (ORDER BY StartTime, EndTime) AS RowID
FROM #table AS T
), createNewTable AS ( -- Recreate table according overlap time
SELECT StartTime, EndTime, RowID
FROM addNR
WHERE RowID = 1
UNION ALL
SELECT
CASE
WHEN a.StartTime <= AN.StartTime AND AN.StartTime <= a.EndTime THEN a.StartTime
ELSE AN.StartTime END AS StartTime,
CASE WHEN a.StartTime <= AN.EndTime AND AN.EndTime <= a.EndTime THEN a.EndTime
ELSE AN.EndTime END AS EndTime,
AN.RowID
FROM addNR AS AN
INNER JOIN createNewTable AS a
ON a.RowID + 1 = AN.RowID
), getMinutes AS ( -- Get difference in minutes
SELECT DATEDIFF(MINUTE,StartTime,MAX(EndTime)) AS diffMinutes
FROM createNewTable
GROUP BY StartTime
)
SELECT SUM(diffMinutes) AS Result
FROM getMinutes
And the result is 160

Answer 2

To get the result with the data you gave, I assume that the end time is not included (otherwise it would be 91 minutes for the first run). With that in mind, this will give you the result you want with no cursors or loops. If the times span multiple days, the logic will need to be adjusted.
--Create sample data
CREATE TABLE TimesToCheck
([StartTime] datetime, [EndTime] datetime)
;
INSERT INTO TimesToCheck
([StartTime], [EndTime])
VALUES
('2014-10-01 10:30:00', '2014-10-01 12:00:00'),
('2014-10-01 10:40:00', '2014-10-01 12:00:00'),
('2014-10-01 10:42:00', '2014-10-01 12:20:00'),
('2014-10-01 10:40:00', '2014-10-01 13:00:00'),
('2014-10-01 10:44:00', '2014-10-01 12:21:00'),
('2014-10-13 15:50:00', '2014-10-13 16:00:00')
;--Now the solution.
;WITH
E1(N) AS (
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1
), -- 1*10^1 or 10 rows
E2(N) AS (SELECT 1 FROM E1 a, E1 b), -- 1*10^2 or 100 rows
E4(N) AS (SELECT 1 FROM E2 a, E2 b), -- 1*10^4 or 10,000 rows
N AS (SELECT TOP (3600) ROW_NUMBER() OVER (ORDER BY (SELECT NULL))-1 AS Number FROM E4),
TimeList AS (SELECT CAST(DATEADD(minute,n.number,0) as time) AS m FROM N),
--We really only need the Timelist table. If it is already created, we can start here.
ActiveTimes AS (SELECT DISTINCT t.m FROM TimeList T
INNER JOIN TimesToCheck C ON t.m BETWEEN CAST(c.StartTime as time) AND CAST(DATEADD(minute,-1,c.EndTime) as time))
SELECT COUNT(*) FROM ActiveTimes