php – 如何使这个MySQL Count查询更有效？

//get the current member count
$sql = ("SELECT count(member_id) as total_members from exp_members");
$result = mysql_query($sql) or die(mysql_error());
$num_rows = mysql_num_rows($result);
if ($num_rows != 0) {
    while($row = mysql_fetch_array($result)) {
        $total_members = $row['total_members'];
    }
}

//get list of products
$sql = ("SELECT m_field_id,m_field_label from exp_member_fields where m_field_name like 'cf_member_ap_%' order by m_field_id asc");
$result = mysql_query($sql) or die(mysql_error());
$num_rows = mysql_num_rows($result);

if ($num_rows != 0) {

    while($row = mysql_fetch_array($result)) {

        $m_field_id             = $row['m_field_id'];
        $m_field_label          = $row['m_field_label'];

        $sql2 = ("SELECT count(m_field_id_".$m_field_id.") as count from exp_member_data where m_field_id_".$m_field_id." = 'y'");
        $result2 = mysql_query($sql2) or die(mysql_error());
        $num_rows2 = mysql_num_rows($result2);

        if ($num_rows2 != 0) {
            while($row2 = mysql_fetch_array($result2)) {
                $p = ($row2['count']/$total_members)*100;
                $n = $row2['count'];
                $out .= '<tr><td>'.$m_field_label.'</td><td>'.number_format($p,1).'%</td><td>'.$n.'</td></tr>';
            }
        }

    }


}