use strict;

$sth = $dbh->prepare(qq{

  SELECT 
    report_no,
    reported_by,
    project_no,
    to_char(date_reported,'DD-MON-YYYY'),
    cat1
    .
    .
    .
    cat15
	  FROM TABLE
       		ORDER BY report_no DESC
	      
	  });


$sth->execute();
$array_ref = $sth->fetchall_arrayref();

$i = 0;

foreach $row (@$array_ref) {
  
  ($report_no,$reported_by,$project_no,$date_reported) 
   = @$row[0..3];

  #Categories in each row may have undef elements, replace
  #with a '-'. For defined values, sum them up. This sum is
  #used to calculate the average for each row.
  
  $number = 0;
  $sum = 0;
  foreach $element (@$row[4..18]) {
    if ($element == -1) { $element = '-' }
    else { 
      $element = sprintf "%.2f", $element;
      $sum += $element;
      ++$number;
    }
  }
  
  $row_avge = sprintf "%.2f", $sum / $number;
  
  $i++;
}

$sth->finish();
$dbh->disconnect;