Delete rows in single table in SQL Server where timestamp column differs - sql

Question

I have a table of employee timeclock punches that looks something like this:
| EmployeeID | PunchDate | PunchTime | PunchType | Sequence |
|------------|------------|-----------|-----------|----------|
| 5386 | 12/27/2016 | 03:57:42 | On Duty | 552 |
| 5386 | 12/27/2016 | 09:30:00 | Off Duty | 563 |
| 5386 | 12/27/2016 | 010:02:00 | On Duty | 564 |
| 5386 | 12/27/2016 | 12:10:00 | Off Duty | 570 |
| 5386 | 12/27/2016 | 12:22:00 | On Duty | 571 |
| 5386 | 12/27/2016 | 05:13:32 | Off Duty | 578 |
What I need to do is delete any rows where the difference in minutes between an Off Duty punch and the following On Duty punch is less than, say, 25 minutes. In the example above, I would want to remove Sequence 570 and 571.
I'm already creating this table by pulling all Off Duty punches from another table and using this query to pull all On Duty punches that follow an Off Duty punch:
SELECT * FROM [dbo].[Punches]
INSERT INTO [dbo].[UpdatePunches (EmployeeID,PunchDate,PunchTime,PunchType,Sequence)
SELECT * FROM [dbo].[Punches]
WHERE Sequence IN (
SELECT Sequence + 1
FROM [dbo].[Punches]
WHERE PunchType LIKE 'Off Duty%') AND
PunchType LIKE 'On Duty%'
I have been trying to fit some sort of DATEDIFF query both in this code and as a separate step to weed these out, but have not had any luck. I can't use specific Sequence numbers because those are going to change for every punch.
I'm using SQL Server 2008.
Any suggestions would be much appreciated.

Answer 1

You can assign rownumbers per employee based on punchdate and punchtime and join each row with the next based on ascending order of date and time.
Thereafter, get the rownumbers of those rows where the difference is less than 25 minutes and finally delete those rows.
with rownums as
(select t.*,row_number() over(partition by employeeid
order by cast(punchdate +' '+punchtime as datetime) ) as rn
from t)
,rownums_to_delete as
(
select r1.rn,r1.employeeid
from rownums r1
join rownums r2 on r1.employeeid=r2.employeeid and r1.rn=r2.rn+1
where dateadd(minute,25,cast(r2.punchdate +' '+r2.punchtime as datetime)) > cast(r1.punchdate +' '+r1.punchtime as datetime)
and r1.punchtype <> r2.punchtype
union all
select r2.rn, r2.employeeid
from rownums r1
join rownums r2 on r1.employeeid=r2.employeeid and r1.rn=r2.rn+1
where dateadd(minute,25,cast(r2.punchdate +' '+r2.punchtime as datetime)) > cast(r1.punchdate +' '+r1.punchtime as datetime)
and r1.punchtype <> r2.punchtype
)
delete r
from rownums_to_delete rd
join rownums r on rd.employeeid=r.employeeid and r.rn=rd.rn
Sample Demo
If date and time columns are not varchar but actual date and time datatype, use punchdate+punchtime in the query.
Edit: An easier version of the query would be
with todelete as (
select t1.employeeid,cast(t2.punchdate+' '+t2.punchtime as datetime) as punchtime,
t2.punchtype,t2.sequence,
cast(t1.punchdate+' '+t1.punchtime as datetime) next_punchtime,
t1.punchtype as next_punchtype,t1.sequence as next_sequence
from t t1
join t t2 on t1.employeeid=t2.employeeid
and cast(t2.punchdate+' '+t2.punchtime as datetime) between dateadd(minute,-25,cast(t1.punchdate+' '+t1.punchtime as datetime)) and cast(t1.punchdate+' '+t1.punchtime as datetime)
where t2.punchtype <> t1.punchtype
)
delete t
from t
join todelete td on t.employeeid = td.employeeid
and cast(t.punchdate+' '+t.punchtime as datetime) in (td.punchtime,td.next_punchtime)
;

Answer 2

SQL Server has a nice ability called updatable CTEs. Using lead() and lag(), you can do exactly what you want. The following assumes that the date is actually stored as a datetime -- this is just for the convenience of adding the date and time together (you can also explicitly use conversion):
with todelete as (
select tcp.*,
(punchdate + punchtime) as punchdatetime.
lead(punchtype) over (partition by employeeid order by punchdate, punchtime) as next_punchtype,
lag(punchtype) over (partition by employeeid order by punchdate, punchtime) as prev_punchtype,
lead(punchdate + punchtime) over (partition by employeeid order by punchdate, punchtime) as next_punchdatetime,
lag(punchdate + punchtime) over (partition by employeeid order by punchdate, punchtime) as prev_punchdatetime
from timeclockpunches tcp
)
delete from todelete
where (punchtype = 'Off Duty' and
next_punchtype = 'On Duty' and
punchdatetime > dateadd(minute, -25, next_punchdatetime)
) or
(punchtype = 'On Duty' and
prev_punchtype = 'Off Duty' and
prev_punchdatetime > dateadd(minute, -25, punchdatetime)
);
EDIT:
In SQL Server 2008, you can do use the same idea, just not as efficiently:
delete t
from t outer apply
(select top 1 tprev.*
from t tprev
where tprev.employeeid = t.employeeid and
(tprev.punchdate < t.punchdate or
(tprev.punchdate = t.punchdate and tprev.punchtime < t.punchtime)
)
order by tprev.punchdate desc, tprev.punchtime desc
) tprev outer apply
(select top 1 tnext.*
from t tnext
where tnext.employeeid = t.employeeid and
(t.punchdate < tnext.punchdate or
(t.punchdate = tnext.punchdate and t.punchtime < tnext.punchtime)
)
order by tnext.punchdate desc, tnext.punchtime desc
) tnext
where (t.punchtype = 'Off Duty' and
tnext.punchtype = 'On Duty' and
t.punchdatetime > dateadd(minute, -25, tnext.punchdatetime)
) or
(t.punchtype = 'On Duty' and
tprev.punchtype = 'Off Duty' and
tprev.punchdatetime > dateadd(minute, -25, t.punchdatetime)
);

Answer 3

You could create a DateTime from the Date and Time fields in a CTE and then lookup the next On Duty Time after the Off Duty Time like below:
;
WITH OnDutyDateTime AS
(
SELECT
EmployeeID,
Sequence,
DutyDateTime = DATEADD(ms, DATEDIFF(ms, '00:00:00', PunchTime), CONVERT(DATETIME, PunchDate))
FROM
#TempEmployeeData
where PunchType = 'On Duty'
),
OffDutyDateTime As
(
SELECT
EmployeeID,
Sequence,
DutyDateTime = DATEADD(ms, DATEDIFF(ms, '00:00:00', PunchTime), CONVERT(DATETIME, PunchDate))
FROM
#TempEmployeeData
where PunchType = 'Off Duty'
)
SELECT
OffDutyDateTime = DutyDateTime,
OnDutyDateTime = (SELECT TOP 1 DutyDateTime FROM OnDutyDateTime WHERE EmployeeID = A.EmployeeID AND Sequence > A.Sequence ORDER BY Sequence ASC ),
DiffInMinutes = DATEDIFF(minute,DutyDateTime,(SELECT TOP 1 DutyDateTime FROM OnDutyDateTime WHERE EmployeeID = A.EmployeeID AND Sequence > A.Sequence ORDER BY Sequence ASC ))
FROM
OffDutyDateTime A
OffDutyDateTime OnDutyDateTime DiffInMinutes
----------------------- ----------------------- -------------
2016-12-27 09:30:00.000 2016-12-27 10:02:00.000 32
2016-12-27 12:10:00.000 2016-12-27 12:22:00.000 12
2016-12-28 05:13:32.000 NULL NULL
(3 row(s) affected)

Answer 4

Maybe something like this would be easy to slap in there.. This simply uses a subquery to find the next 'on duty' punch and compare it in the main query to the 'off duty' punch.
Delete
FROM [dbo].[Punches] p
where p.PunchTime >=
dateadd(minute, -25, isnull (
(select top 1 p2.PunchTime from [dbo].[Punches] p2 where
p2.EmployeeID=p.EmployeeID and p2.PunchType='On Duty'
and p1.Sequence < p2.Sequence and p2.PunchDate=p.PunchDate
order by p2.Sequence asc)
),'2500-01-01')
and p.PunchType='Off Duty'