Populate a row in SQL Server based on a condition (query optimization) - sql

Question

I am trying to find all the people who took a timeoff for previous months, I got most of it. But if nobody took a timeoff in the current month, I need to populate a row saying 0 to get my visuals right.
This is what my data looks like:
This is what I have for the visual:
select s.*, DATEPART(MONTH, startd) as timeoff_Mon,
DATEDIFF(day, startd, endd) as timeoff, getdate() as dat,
DATEPART(MONTH, GETDATE()) as Current_Mon from sample s;
You can see that Jack was the only employee who took time off in January for a day, and John in Feb for 4 days,
Now, in March, I have got the current month which is the last column in the image above from the current date.
Using this current month, is there a way to populate a row or hardcode a row to populate the time off column as 0??
Desired Output:
Here is the SQL Fiddle with the above-mentioned problem.
https://dbfiddle.uk/?rdbms=sqlserver_2017&fiddle=9e8fbb2ae8dcfec9cc5fdfa784782753

Answer 1

A simple option is to use union all to add the final record if there is no row that overlaps the current month in the table:
select
s.*,
month(startd) as timeoff_mon,
datediff(day, startd, endd) as timeoff,
getdate() as dat,
month(getdate()) as current_mon
from sample s
union all
select null, null, null, null, null, 0, getdate(), datepart(month, getdate())
where not exists (
select 1
from sample s
where
s.startd < dateadd(mm, datediff(mm, 0, getdate()) + 1, 0)
and s.endd >= dateadd(mm, datediff(mm, 0, getdate()), 0)
)
Demo on DB Fiddle:
Name | ID | STARTD | ENDD | timeoff_mon | timeoff | dat | current_mon
:--------- | ---: | :--------- | :--------- | ----------: | ------: | :---------------------- | ----------:
Jack | 5 | 2020-01-25 | 2020-01-26 | 1 | 1 | 2020-03-28 14:28:56.867 | 3
John | 6 | 2020-02-05 | 2020-02-09 | 2 | 4 | 2020-03-28 14:28:56.867 | 3
null | null | null | null | null | 0 | 2020-03-28 14:28:56.867 | 3