Don't panic, set expressions seems difficult at first sight, but then you'll love working with them.
Let's suppose you have a date field (you don't have to create variables); only a date field will do the job.
And let's suppose you've created a calendar in your script so you have Year,Month, Quarter and Week fields
YTD: if we select 12/04/2016: YTD will return our measure from 01/01/2016 to 12/04/2016
How we do that?
Suppose our measure is : sum(Sales)
1)First changes: sum({<date=,Year=,Month=,Quarter=>}Sales)
We add these to force Qlik to not take into consideration our selection of date for example.
Let me explain in better words, if you don't write the "date=" and select the date 12/04/2016; Qlik will filter all the data to that selected point and then return the sum(Sales) for the day 12/04/2016.
To prohibit this, we must write the date=.
2) Second change: sum({<date=,Year=,Month=,Quarter=, date={">=$(=YearStart(Max(date)))<=$(=Max(date))"}>}Sales)
Let explain this : date={">=$(=YearStart(Max(date)))<=$(=Max(date))"}
We want to work from date=01/01/2016 to the selected date=12/04/2016 right?
So we're working with the field :
a) date={ }
b) Now we wanna this date to be <=selected date which is max(date) ;
max(date) is a function so it needs an "=" sign:
=max(date)
when we have a '=' we add the $ (before each calculation) : $(=max(date) ) => this is 12/04/2016
Now we add the <= so we'll have : <=$(=max(date) )
for the second part, we want our date to be >=01/01/2016 which is the start of the year:
a) same approach, we use the YearStart function that returns the start of the selected year: >=$(=YearStart(Max(date)))
Now our expression is : from : date={ }
to : date={>=$(=YearStart(Max(date)))<=$(=Max(date))}
Now, in a set expression, if we wanna work with the year 2016 for example which is numeric: we call it without quotes:
Year={2016}
If we wanna focus on a country, Tunisia for example which is a string: we call it with quotes
Country={'Tunisia'}
In our case, we focusing on a range of dates created by an expression, so we surround it by double quotes:
date={">=$(=YearStart(Max(date)))<=$(=Max(date))"}
Final expression for YTD:
sum({<date=,Year=,Month=,Quarter=, date={">=$(=YearStart(Max(date)))<=$(=Max(date))"}>}Sales)
Same approach for MTD:
sum({<date=,Year=,Month=,Quarter=, date={">=$(=MonthStart(Max(date)))<=$(=Max(date))"}>}Sales)
Hope this helps,
Omar,
