Counting consecutive days including weekends SQL Server - sql

Question

I have an sql query that counts consecutive days but i need it to count weekends to. For example, if someone has a friday and a monday off i need this to count as 2 consecutive days if that makes sense.
tables:
CREATE TABLE Absence(
Date Date,
Code varchar(10),
Name varchar(10),
Type varchar(10)
);
INSERT INTO Absence (Date, Code, Name, Type)
VALUES ('01-10-18', 'S', 'Sam', 'Sick'),
('01-11-18','S', 'Sam', 'Sick'),
('01-12-18','S', 'Sam', 'Sick'),
('01-21-18','S', 'Sam', 'Sick'),
('01-26-18','S', 'Sam', 'Sick'),
('01-27-18','S', 'Sam', 'Sick'),
('02-12-18','S', 'Sam', 'Holiday'),
('02-13-18','S', 'Sam', 'Holiday'),
('02-18-18','S', 'Sam', 'Holiday'),
('02-25-18','S', 'Sam', 'Holiday'),
('02-10-18','S', 'Sam', 'Holiday'),
('02-13-18','F', 'Fred', 'Sick'),
('02-14-18','F', 'Fred', 'Sick'),
('03-09-18','F', 'Fred', 'Sick'),
('03-12-18','F', 'Fred', 'Sick'),
('02-28-18','F', 'Fred', 'Sick');
I have this code:
select name, min(date), max(date), count(*) as numdays, type
from (select a.*,
row_number() over (partition by name, type order by date) as
seqnum_ct
from absence a
) a
group by name, type, dateadd(day, -seqnum_ct, date);
And it produces this result:
| name | | | numdays | type |
|------|------------|------------|---------|---------|
| Fred | 2018-02-13 | 2018-02-14 | 2 | Sick |
| Fred | 2018-02-28 | 2018-02-28 | 1 | Sick |
| Fred | 2018-03-09 | 2018-03-09 | 1 | Sick |
| Fred | 2018-03-12 | 2018-03-12 | 1 | Sick |
| Sam | 2018-02-10 | 2018-02-10 | 1 | Holiday |
| Sam | 2018-02-12 | 2018-02-13 | 2 | Holiday |
| Sam | 2018-02-18 | 2018-02-18 | 1 | Holiday |
| Sam | 2018-02-25 | 2018-02-25 | 1 | Holiday |
| Sam | 2018-01-10 | 2018-01-12 | 3 | Sick |
| Sam | 2018-01-21 | 2018-01-21 | 1 | Sick |
| Sam | 2018-01-26 | 2018-01-27 | 2 | Sick |
If you look at these lines
('03-09-18','F', 'Fred', 'Sick'),
('03-12-18','F', 'Fred', 'Sick'),
This should equal 1 consecutive period even though it is a Friday and a Monday if this make sense. How can i edit this code so that it includes weekends to?
Thanks
SQL fiddle - http://sqlfiddle.com/#!18/1de27/1

Answer 1

Try this:
select name, min(date), max(date), count(*) as numdays, type
from (
select date, code, name, type, seqnum_ct + sum(weekend) over (partition by name, type order by date) seqnum_ct
from (select a.*,
row_number() over (partition by name, type order by date) as seqnum_ct,
case when datepart(weekday, [date]) = 2 and
datepart(weekday, lag([date]) over (partition by name, type order by date)) = 6 then 2 else 0 end [weekend]
from #absence a
) a
) a
group by name, type, dateadd(day, -seqnum_ct, date);

Answer 2

You can use a running sum to create groups to handle weekends. All you need to check is the current row's weekday is 2 (for Monday) and the previous row's is 6 (for Friday), for a given name,type in date order.
select name, min(date), max(date), count(*) as numdays, type
from (select a.*,sum(col) over(partition by Name,type order by [Date]) as grp
from (select a.*,
case when datediff(day,lag([Date]) over(partition by Name,type order by [Date]),[Date])=1 or
(datepart(weekday,[Date])=2 and datepart(weekday,lag([Date]) over(partition by Name,type order by [Date]))=6)
then 0 else 1 end as col
from absence a
) a
) a
group by name, type, grp