$sth = $dbh->prepare("Select * FROM datatable");
$sth->execute;
my %map;
{
   my @col = @{ $sth->{NAME_lc} };
   for (0..$#col) { $map{$col[$_]} = $_ }
}
while( my $row = $sth->fetchrow_arrayref ) {
   # I want the cols named ID, name, city, in that order
   printf "%d: %s from %s\n"
     ,$row->{$map{id}}
     ,$row->{$map{name}}
     ,$row->{$map{city}};
}