Need to delete three consecutive days excluding weekends and holidays in sql - sql

Question

I have a requirement to delete rows from a table with three consecutive days (exclude the days if weekends come in between)
CREATE TABLE [dbo].[Test]
(
[Scanid] [bigint] NULL,
[Employeeid] [int] NULL,
[Datescanned] [datetime] NULL
)
INSERT INTO [dbo].[Test]([Scanid], [Employeeid], [Datescanned])
VALUES (108639, 3820, '2016-04-28 17:12:33.000'),
(108639, 3820, '2016-04-28 18:05:46.000'),
(108639, 3820, '2016-04-28 20:58:36.000'),
(999999, 3820, '2016-04-29 10:08:00.000'),
(999999, 3820, '2016-04-29 10:12:10.000'),
(777777, 3820, '2016-05-02 10:12:00.000'),
(111111, 3820, '2016-04-04 10:12:00.000'),
(33333, 3820, '2016-04-11 17:23:00.000'),
(987623, 3820, '2016-04-18 11:12:00.000'),
(1234, 3820, '2016-05-26 10:00:00.000'),
(5678, 3820, '2016-05-27 10:00:00.000'),
(8920, 3820, '2016-05-31 10:00:00.000')
Output:
Scanid Employeeid Datescanned
----------------------------------------
108639 3820 2016-04-28 17:12:33.000
108639 3820 2016-04-28 18:05:46.000
108639 3820 2016-04-28 20:58:36.000
999999 3820 2016-04-29 10:08:00.000
999999 3820 2016-04-29 10:12:10.000
777777 3820 2016-05-02 10:12:00.000
111111 3820 2016-04-04 10:12:00.000
33333 3820 2016-04-11 17:23:00.000
987623 3820 2016-04-18 11:12:00.000
1234 3820 2016-05-26 10:00:00.000
5678 3820 2016-05-27 10:00:00.000
8920 3820 2016-05-31 10:00:00.000
We can take date only from datescanned field and then in the above example we should delete rows with 3 consecutive date from '2016-04-28' to '2016-05-02' (2016-04-30 and 31 are weekends so we can ignore) and also delete rows with 3 consecutive date from '2016-05-26' to '2016-05-31' (2016-05-29 and 30th are weekends so we can ignore). so only results should display row with days 2016-04-04,2016-04-11,2016-04-18 which don't have 3 consecutive days before or after them.

Answer 1

Here is the exact output that you want..
I could see one mistake in your question,[ie. delete rows with 3 consecutive date from '2016-05-26' to '2016-05-31' (2016-05-29 and 30th are weekends so we can ignore)'],those weekends days are not correct..and the correct dates are 2016-05-28 and 2016-05-29.
DROP TABLE [TestDates]
GO
CREATE TABLE [dbo].[TestDates](
[Scanid] [bigint] NULL,
[Employeeid] [int] NULL,
[Datescanned] [datetime] NULL
)
INSERT INTO [dbo].[TestDates] ([Scanid] ,[Employeeid],[Datescanned])
VALUES (108639,3820,'2016-04-28 17:12:33.000'),(108639,3820,'2016-04-28 18:05:46.000'),
(108639,3820,'2016-04-28 20:58:36.000'),(999999,3820,'2016-04-29 10:08:00.000'),
(999999,3820,'2016-04-29 10:12:10.000'),(777777,3820,'2016-05-02 10:12:00.000'),
(111111,3820,'2016-04-04 10:12:00.000'),(33333,3820,'2016-04-11 17:23:00.000'),
(987623,3820,'2016-04-18 11:12:00.000'),(1234,3820,'2016-05-26 10:00:00.000'),
(5678,3820,'2016-05-27 10:00:00.00'), (8920, 3820, '2016-05-30 10:00:00.000')
GO
DROP TABLE #t
GO
SELECT DISTINCT Employeeid,CONVERT(date,Datescanned) Datescanned INTO #T
FROM [TestDates]
GO
;WITH cte_cnt
AS
(
SELECT Employeeid, MIN(Datescanned) AS FROM_DATE
,MAX(Datescanned) AS TO_DATE
, COUNT('A') AS DayDiff
FROM (
SELECT Employeeid,Datescanned,
ROW_NUMBER() OVER(ORDER BY Datescanned) AS ROW_NUMBER,
DATEDIFF(D, ROW_NUMBER() OVER(ORDER BY Datescanned)
,CASE WHEN DATENAME(dw, cast (Datescanned as datetime)-1) = 'Sunday' THEN DATEADD(DAY, -2, Datescanned) ELSE Datescanned END) AS Diff
FROM #t) AS dt
GROUP BY Employeeid, Diff )
DELETE t
--SELECT *
FROM cte_cnt c
JOIN [TestDates] t
ON c.Employeeid=t.Employeeid
WHERE CAST(t.Datescanned as DATE) BETWEEN c.FROM_DATE AND c.TO_DATE and c.DayDiff=3
GO
SELECT *
FROM [TestDates]
GO

Answer 2

A solution which doesn't account for holidays would be
SELECT
t.*
FROM (SELECT DISTINCT
CAST(t1.datescanned AS date) first_date,
CAST(t2.datescanned AS date) second_date,
CAST(t3.datescanned AS date) third_date
FROM test t1
JOIN test t2 --add a join condition for employeeid as well
ON DATEDIFF(dd, CAST(t1.datescanned AS date), CAST(t2.datescanned AS date)) = 1
OR (DATEPART(WEEKDAY, CAST(t2.datescanned AS date)) = 2
AND DATEDIFF(dd, CAST(t1.datescanned AS date), CAST(t2.datescanned AS date)) = 3)
JOIN test t3 --add a join condition for employeeid as well
ON DATEDIFF(dd, CAST(t2.datescanned AS date), CAST(t3.datescanned AS date)) = 1
OR (DATEPART(WEEKDAY, CAST(t3.datescanned AS date)) = 2
AND DATEDIFF(dd, CAST(t2.datescanned AS date), CAST(t3.datescanned AS date)) = 3)
) x
JOIN test t
ON CAST(t.datescanned AS date) = x.first_date
OR CAST(t.datescanned AS date) = x.second_date
OR CAST(t.datescanned AS date) = x.third_date
Self join the table twice, each time on
a date difference of 1 or
3 when a weekend occurs and check if the weekday is Monday (weekday=2)
Sample demo
The result gives the rows which need to be deleted. But the caveat here is that, this would give you more than 3 consecutive days if there are no gaps. In that case you need to explain if you want to stop deleting at the 3rd day.

Answer 3

The previous scripts are good. I would make an improvement and for weekend and Holiday check, add a function and call it in the select statement.
Here is a simple function that you can use (I am assuming that you have a table called Holiday, which holds all holiday dates per State )
Create FUNCTION [dbo].[IsHolidayOrWeekend]
(
#date DateTime,
#stateId int
)
RETURNS Bit
AS
BEGIN
declare #dayOfWeek VARCHAR(9);
set #dayOfWeek = DATEName(DW, #date);
IF(#dayOfWeek = 'Saturday' OR #dayOfWeek = 'Sunday')
RETURN 1;
ELSE
begin
set #date = cast(#date as date) -- Remove the time portion
RETURN IsNull((SELECT 1 from Holiday where StateId = #provinceId and HolidayDate = #date ), 0)
end;
END

Answer 4

Perhaps this?:
delete from Test
where not exists (
select 1
from Test t2
where cast(t2.Datescanned as date)
between
dateadd(day,
case datepart(dayofweek, cast(Test.Datescanned as date))
when 1 then -4 when 2 then -4
else -2
end,
cast(Test.Datescanned as date)
)
and
dateadd(day,
case datepart(dayofweek, cast(Test.Datescanned as date))
when 4 then 4 when 5 then 4
else 2
end,
cast(Test.Datescanned as date)
)
)

Answer 5

I have an added requirement to igonre holidays also along with weekend. I cretaed Test_calendar table removing all holidays and weekends and assigned row number to active days. Then this is the code I used. It working but may not be the fast if we have millions of rows. For me data is small so it will get the work done. Please let me know if you can simplify deletion process to make it fast.
SELECT distinct scanid as [badgeid] , Employeeid,CONVERT(date, Datescanned) as Datescanned,RN
into #test1
FROM [dbo].[Test] a
inner join Test_Calendar b
on CONVERT(date, a.Datescanned)=b.Cal_date
order by Datescanned asc
declare #min int
declare #max int
declare #i int
select #min=MIN(rn) from #test1
select #max=Max(rn) from #test1
while(#min<#max)
begin
select #i=COUNT(*) from #test1 where rn in(#min ,#min+1,#min+2)
if(#i=3)
select * from #test1 where rn in(#min ,#min+1,#min+2)
set #min=#min+1
end