$sth->execute() or die "Cannot execute: " . $sth->errstr();

my %hash;
while ( my( $district, $ID ) = $sth->fetchrow_array ) {
    $hash{ $district } = $ID;
}

# A number of ways to do it here, this is the best if you
# don't know you have an exact multiple of 3....

my @keys = sort keys %hash;   # sort by district
my $column=0;
print "<TABLE>\n";
while ( my $dis = shift @keys ) {
  if ( $column == 0 ) { 
    print "<TR>\n";
  }
  print "<TD><A HREF=\"", $hash{ $dis }, "\">", $dis, "</a></TD>";
  if ( $column == 2 ) { 
    print "</TR>\n";
    $column = 0;
  } else {
    $column++;
  }
}
# Print trailing TR if needed
if ( $column != 0 ) {
  print "</TD>\n";
}
print "</TABLE>\n";