how do i automatically update a column list box after user enters two codes?

[angel duran]

Hi... i'm trying to accomplish this and i will be using some pictures
so you can easily follow me along.
I have this form <link>http://img30.exs.cx/my.php?loc=img3 0&image=4214.jp g</link>
and in the products subform column where it says "productID" it's a
list box <link>http://img30.exs.cx/img30/4361/4215.jpg</link>and
the user can browse through the products and after he selects one, the
supplier column, the code column,
and the description column are automatically updated with the selected
product id (i used an inner join to
accomplish this). Now i want to add a second and a third column in the
"products subform" like this:
<link>http://img30.exs.cx/img30/8381/4216.jpg</link>I inserted these
two columns in my "subform design view", so these two columns are not
stored in a table nor a query ( i used the wizard for the subform).
Now, all the products' information such as supplier code, and
supplier's product code are stored in my "products" query. Now, why
would i need to update the productId list column? because my
relationships are based on the "productID" , and now some of the users
find it easier to type the two-letter supplier code and suplier's
product code instead of scrolling and browsing through the 2225
products (obviously :P). So the user types in column s1 "AA" and then
types in column C1 "01", the productID column will be automatically
updated with the number where that product exists, and i believe if
the productID column is updated like that, the description column will
also be updated. any suggestions?. Thank you so much in advance for
your time and patience.

[Pieter Linden]

base your subform on a query, not a table.