How do I produce a report to show the number of occurrences an employee has been absent from work - tsql

Question

I have been asked to generate a report to show the number of occurrences an employee is absent from work sick.
If an employee is absent from work for 3 consecutive days this will be counted as 1 occurrence. If they then return to work and are then absent again for another 2 consecutive days this will be recorded as 2 occurrences.
I need to generate a report to show the number of occurrences an employee is away from work sick within a 6 month period.
I have set out an example below of the data showing an employee's absence records and how i need the report to look.
How data shows in database:
enter image description here
Name Absence Dates
John Smith 01-Sep-19
John Smith 02-Sep-19
John Smith 03-Sep-19
John Smith 10-Sep-19
John Smith 11-Sep-19
How i wish for the report to look:
Name Occurrences
John Smith 2
I would be grateful for any assistance with writing to code to achieve this result.

Answer 1

Not a full answer, as you should really do some of this yourself, however, based on what you have detailed in your quesiton, you could use the approach below to count up any spells of absence, within a 6 month period.
Assumes you would be compiling this using SQL Server
declare #absences table (empid nvarchar(10), [abs date] date, [ret date] date);
declare #staff table ([empid] int, [name1] nvarchar(50), [name2] nvarchar(50), [surname] nvarchar(50));
-- put some test values in the staff table to work with
insert into #staff
values
(1, 'John', 'Lewis', 'Smith'), -- using a unique ID here, in any good system this should be an incremental number for each new staff member added to the table
(2, 'James', 'Thomas', 'Brown')
-- put some test values in the absences table to work with
insert into #absences
values
(1, '2019-07-01', '2019-07-04'), -- userid, absence date & return date
(1, '2019-08-04', '2019-08-06'),
(2, '2019-07-02', '2019-07-05'),
(2, '2019-08-05', '2019-08-07')
select count(*) spellsoff, empid, name1, name2, surname, [days absent]
from
(
select
s.empid,
s.name1,
s.name2,
s.surname,
a.[abs date],
a.[ret date],
datediff(d,a.[abs date], a.[ret date]) [days absent]
from #staff s
left join #absences a
on s.empid = a.empid
where [abs date] >= DATEADD(M,-6,GETDATE()) -- pull back those employeess that have been absent in the last 6 months from today's date
)doff
group by empid, name1, name2, surname, [days absent]
Gives you the following breakdown:
spellsoff empid name1 name2 surname days absent
1 1 John Lewis Smith 2
1 1 John Lewis Smith 3
1 2 James Thomas Brown 2
1 2 James Thomas Brown 3