Variables in set Analysis

[Anonymous]

How can I use a variable in a set analysis expression?

[#2]

Oleg (and everyone)-

This is wonderfully helpful. That being said, how do I set up set analysis (with variables) to sum up specific values contained in the output of the variables?  Here's an example expression:

=sum({<Product.ProdName={'$(vProd1)'}>}

Product.ProdValue) + sum({<Product.ProdName={'$(vProd2)'}>}

Product.ProdValue) + sum({<Product.ProdName={'$(vProd3)'}>}

Product.ProdValue) + sum({<Product.ProdName={'$(vProd4)'}>}

Product.ProdValue)

The above expression works absolutely fine.  I need a totals column. That being said, the values contained in vProd1, vProd2, (so on...) contain either a "ProdA" or "ProdB" contained in the ProductName (which is pulled in based on the variable).  I need to sum up all values containing "ProdA" and sum up all values containing "ProdB" each in it's own column.  What's the best way of accomplishing this?

Also...  I have to imagine this can be highly intensive (or could be).  I've provided a highly shorted version of this expression above.  Additionally, there are always hundreds of Products being added everyday.  So, I don't want to run into an "Out of memory" situation.  So also looking for efficient ways of handling this situation as well.

Thanks!