Change output according to LAG - sql-server

Question

I have the current issue:
I'm trying to get the amount of time each of our workers have worked in a day to calculate our company's productivity. We have the time each of our workers has entered and left the building.
The rule is, sometimes our workers leaves the building to smoke or get something from the news stand outside, so we don't take that into consideration and count as if the person never left the building.
We have a cafeteria inside our building so most people don't actually leave the building to have lunch/dinner, so we just remove 1 hour from their productivity calculation, but, if they leave for more then 45 minutes, we will consider that the worker left to lunch/dinner.
I need the end result to look like this:
+----------+----------------+----------------+---------+----------+
| PersonID | IN | OUT | MINUTES | EatOut |
+----------+----------------+----------------+---------+----------+
| 1 | 20170807 08:00 | 20170807 17:25 | 465 | 1 |
+----------+----------------+----------------+---------+----------+
| 2 | 20170807 08:00 | 20170807 17:00 | 540 | 0 |
+----------+----------------+----------------+---------+----------+
My query I have so far:
DECLARE #mytable TABLE(
PersonId INT,
Situation VARCHAR(3),
SituationDtm DATETIME
);
INSERT INTO #mytable VALUES
(1, 'IN', '20170807 08:00'),
(1, 'OUT', '20170807 12:30'),
(1, 'IN', '20170807 14:00'),
(1, 'OUT', '20170807 17:15'),
(2, 'IN', '20170807 08:00'),
(2, 'OUT', '20170807 09:15'),
(2, 'IN', '20170807 09:30'),
(2, 'OUT', '20170807 17:00');
WITH CTE AS (
SELECT
[PersonId],
Situation AS 'CUR.Situation',
SituationDtm AS 'CUR.SituationDtm',
LEAD(Situation) OVER(PARTITION BY PersonId ORDER BY SituationDtm) AS 'NEXT.Situation',
LEAD(SituationDtm) OVER(PARTITION BY PersonId ORDER BY SituationDtm) AS 'NEXT.SituationDtm'
FROM
#mytable
)
SELECT
[CUR.Situation],
[CUR.SituationDtm],
[NEXT.Situation],
[NEXT.SituationDtm],
DATEDIFF(MINUTE, [CUR.SituationDtm], [NEXT.SituationDtm]) AS 'MINUTES'
FROM
CTE
Thanks in advance

Answer 1

You can further query as below: Since you are looking your solution in SQL Server 2008 where you do not have lead/lag you can query as below:
;With Cte as (
Select *, RowN = Row_Number() over(Partition by PersonId order by SituationDtm) from #mytable
), Cte2 as (
Select c1.*, c2.Situation as NextSituation, c2.SituationDtm as NextSituationDtm from cte c1 left join cte c2 on c1.RowN+1 = c2.RowN
and c1.PersonId = c2.PersonId
)
Select PersonId,
Min(SituationDTM) as [In],
Max(Situationdtm) as [Out],
Sum(Case when Situation = 'OUT' and NextSituation = 'IN' and datediff(mi,SituationDtm, NextSituationDTM) > 60 then 1 else 0 end) EatOut,
Sum(Case when Situation = 'OUT' and NextSituation = 'IN' and datediff(mi,SituationDtm, NextSituationDTM) > 60 then 0 else datediff(mi,SituationDtm, NextSituationDTM) end) as [minutes]
from Cte2
group by PersonId
In later versions after >= 2012 you can query as below:
Select PersonId,
Min(SituationDTM) as [In],
Max(Situationdtm) as [Out],
Sum(Case when Situation = 'OUT' and NextSituation = 'IN' and datediff(mi,SituationDtm, NextSituationDTM) > 60 then 1 else 0 end) EatOut,
Sum(Case when Situation = 'OUT' and NextSituation = 'IN' and datediff(mi,SituationDtm, NextSituationDTM) > 60 then 0 else datediff(mi,SituationDtm, NextSituationDTM) end) as [minutes]
from (
Select *, NextSituationDTM = lead(situationdtm) over (partition by personid order by situationdtm),
NextSituation = lead(Situation) over (partition by personid order by situationdtm) from #mytable
) a
group by PersonId
Output as below:
+----------+-------------------------+-------------------------+--------+---------+
| PersonId | In | Out | EatOut | minutes |
+----------+-------------------------+-------------------------+--------+---------+
| 1 | 2017-08-07 08:00:00.000 | 2017-08-07 17:15:00.000 | 1 | 465 |
| 2 | 2017-08-07 08:00:00.000 | 2017-08-07 17:00:00.000 | 0 | 540 |
+----------+-------------------------+-------------------------+--------+---------+