HOWTO create a table of variables witch can be edited by QV user?

[#1]

hellow there,

I`d like to create a bunch of variables (in some kind of structure like table or sth.) witch can be edited by QV user and this variables affects the results presented in application.

The problem is connected with currency exchange defined by every month-year, so the QV app user can edit structure like below:

  Table 1.

Currency	Book Month	Rate
USD	2011-06-01	2.75
USD	2011-05-01	2.77
USD	2011-04-01	2.91
USD	2011-03-01	2.94
USD	2011-02-01	2.88
USD	2011-01-01	3.05
EUR	2011-06-01	3.95
EUR	2011-05-01	3.99
TND	2011-04-01	4.06
EUR	2011-03-01	4
GBP	2011-02-01	3.89
EUR	2011-01-01	4
…

Lets say we give him a possibility to select single 'Currency+Book_Month' and then edit 'Rate' using Spinner component.

Looking at the data logic we have a product bouhgt in some date, which contains a parts - each part`s cost is described in different currency with Rate determined by 'Currency' and 'Book_Month' from table above.

For specific product we calcuate real cost transfering all costs in to one currency calculating it using table   'Table 1' and combining it by Table2.'Book date' with  Table1.'Book Month' and Table1.'Currency' with Table2.Part_1_Currency, Table2.Part_2_Currency and Table2.Part_3_Currency.

Table 2.

Product_id	Book date	Part_1_Currency	Part_1_Cost	Part_2_Currency	Part_2_Cost	Part_3_Currency	Part_3_Cost
1	2011-06-23	USD	39	EUR	56	TND	75
2	2011-05-04	EUR	56	EUR	78	TND	89
3	2011-02-23	GBP	34	EUR	23	MAD	32

QV User by editing currency rates in 'table 1' can speculate how high product`s cost could be if the currency rate changes. 'Table 1' can be staticly set at the begining and then while changing by user product`s cost will be recalculated.

Questions:

1. how to dynamicly define in QV structure of variables  like in 'Table 1' and connect them with QV component, in order to changing them by user, wihout reloading all application? (defining a single variable multiple times and managing it is realy annoying).

2. If we make a pivot with aggregation   sum(product`s_cost) how to dynamicly calculate cost_of_all_products while assumpions in 'Table 1' are being changed by QV user? maybe use an external funtion witch takes as args. info about product, then calculates cost based on Table1? But I don`t have a clue if this kind of funtions can be written in qv scripting? maybe it has to be external written in VBA, Python...?

thanks for any ideas with this stuff.