Calculating a cummulative measure is common query in DW, but there is no straight forward way in DI. Either you have to write a custom function or you have to design using query transform.

I have a source data like this,

I want target data like this,

Well will see the design, here i have two QRY instances and generating a row number in each instance

will do a self join on the basis of RNUM and then summing up the credit value

and grouping the values based on Year & Month in the same QRY instance

and then apply order by on the basis of Year and Credit in another QRY instance

Execute the job, you’ll get the desired output.