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I need help doing some basic arithmatic on some database values. Initi
+ally, I query my table for all product codes and quantity ( using DBI
+ ). Then I display these non-editable values along with two editable 
+fields for entering a value that will be added/subtracted from origin
+al quantity in a form (using CGI) so it looks something like this: 

...
.

What I need to do happen when the form is submitted is take all the in
+put in the add and/or subtract fields and do the appropriate math on 
+the original quantity value, then store the newly calculated quantity
+ back into the table. Can anyone please give me a good example to wor
+k with?

use CGI;
my $q = CGI->new;
...
    my $sql = qq(update table set qty = qty + $qty where key = $key);
    # do you need DBI help here?
}