必要な SQL は、おそらく次のようなものです。
SELECT YEAR(date) AS year, MONTH(date) AS month, COUNT(*) AS entries FROM my_table
GROUP BY year,month ORDER BY year ASC, month ASC;
コードは次のようになります。
$previous_year = null;
foreach ($result_rows as $row) {
if ($previous_year == null || $row['year'] != $previous_year) {
if ($previous_year != null) {
echo '</ul>/li>';
}
echo '<li><span class="year">'.$row['year'].'</span><ul>';
$previous_year = $row['year'];
}
echo '<li>'.$row['month'].' ('.$row['entries'].')</li>';
}
if ($previous_year != null) {
echo '</ul></li>';
}
編集:
別の答えに基づく代替PHP、これはより整頓されています:
$grouped = array();
foreach ($result_rows as $row) {
$grouped[$row['year']][$row['month']] = $row;
}
foreach ($grouped as $year => $months) {
echo "<li>$year";
echo "<ul>";
foreach ($months as $month => $row) {
echo "<li>$month (".$row['entries'].")</li>";
}
echo "</ul></li>";
}