# assuming $cgi = new CGI;

# prepare update query
my $sth = $dbh->prepare(' update pic_table set pic_value=? where pic_id=? ');

# loop over all param names, and
# grep out all those that are numerical
foreach my $p( grep /^\d+$/, $cgi->param) {

    # find the form value
    my $v = $cgi->param( $p );

    # execute the query
    $sth->execute( $v, $p );
}