How to use variable in set analysis ?

[#1]

Hello everyone,

In my application, there are data for several years and I would like to show in a graph only the last 3 years (current one + 2 laters).

So I created a variable : vCurrentYear = max(MyYear)    // MyYear is a field in my calendar that goes until the date of execution.

If I put =$(vCurrentYear)  in a textbox, I do get 2015.

In my graph, in the expression tab, I have entered  in order to get the sum of Cpt_abt for the past 3 years.

sum({$<Year_S={">=$(vCurrentYear)-2"}>}Cpt_abt)

But I get the message "No data to display".

If instead, I put

sum({$<Year_S={">=2013"}>}Cpt_abt)   , I do get my graph.

I am guessing there must be something wrong with the quotations marks but I cannot find the proper way to write my expression..

Any ideas ?

Thank you for your help

[#2]

This works ! Thank you !

Now, I would like to understand what does the equal sign do ? What does "evaluate globally" mean ? I I don't put the equal sign, it is "locally" evaluated ?

[luciancotea]

http://community.qlik.com/blogs/qlikviewdesignblog/2014/11/24/the-equal-sign

[jonathandienst]

Without the = sign, you are inserting the expression and the expression is evaluated after expansion. That's why you use =$(var) in the text box. The expression is expanded and then evaluated.

With the = sign, the variable is evaluated continuously and the value itself is inserted. Now you can use

=var in the text box, because var has already been calculated.

HTH

Jonathan