SQL Sub Query Equivalent in Qlik Sense

[#1]

Table:

Date,Sales

08-06-2016,9

12-06-2016,3

20-07-2016,9

14-07-2016,1

19-08-2016,10

22-08-2016,2

25-12-2016,0

OutPut:

Date,Sales,Selective_Sum

18-06-2016,9,0

12-06-2016,3,9

20-07-2016,9,12

14-07-2016,1,21

19-08-2016,10,23

22-08-2016,2,20

25-12-2016,0,0

Logic: Selective_Sum = Sum of Sales in Last Two Months from the current date for each row.

If I were to do this is SQL ,that would be a piece of cake using a subquery.

Note: You are free to order things up.

Note: There are gaps between the dates.

Please avoid loops,Above, Aggr if possible.

Thanks alot in advance.

[Gysbert_Wassenaar]

Please don't clutter this site with duplicate discussions: SQL SubQuery Equivalent in QlikScript?

[#3]

Ty for your concern for this site, I want to point out the key difference b/w those two question, kindly look into the date gaps between input sample space of each scenarios, Which is the realistic problem that I am trying to solve this past week. Hope I'll get a positive reply!