Question

I want to get the value from an array thats in a while fetchrow.. if that makes sense.
heres my code and the output to help explain

while (@data = $STH2->fetchrow_array()) {

                           print "<tr>";
                           print "<td>$_</td>" for @data[0,1];

                           print "</tr>";

and this outputs

$data[0]   |  $data[1]
   1       |    1000
   1       |    400
   12      |    500
   12      |    150   

(each $data[0] will only output 2 values)

what i want to do is subtract the 2 $data[1] values from each other (ie. 1000-400) for each different $data[0] value then print that. I cant figure out how to do this, thank you for any help.

Answer 1

Just capture the values in a hash of array references and then do the subtraction later (Warning: Untested):

my %data_hash=(); #keys: $data[0], values: array ref of $data[1] corresponding to $data[0]

while(@data=$STH2->fetchrow_array)
{
  push @{$data_hash{$data[0]}},$data[1];
}

foreach(sort{$a<=>$b}(keys %data_hash))
{
  print "<tr>";
  print "<td>$_</td>";
  my $diff=$data_hash{$_}->[0] - $data_hash{$_}->[1];
  print "<td>$diff</td>";
  print "</tr>";
}