# %yearly_page_hits defined elsewhere

my %new_monthly_page_hits;

# do this outside of the loop
my $dbh = DBI->connect("DBI:mysql:$sqlDatabaseName:","$mysqlUsername","$mysqlPassword")
    or die "Connection Error: $DBI::errstr\n";

# loop through page keys
foreach my $page (keys %yearly_page_hits) {
    # a single DBI call does it all
    if (my @row = $dbh->selectrow_array(
        "select count(page) from counter_monthly where page='$page'")) {
        $new_monthly_page_hits{$page} = $row[0];
    }
    else {
        $new_monthly_page_hits{$page} = 0;
    }
    print "$page $new_monthly_page_hits{$page}<br><br>";
}