statistics.php

<?php

$dsn = 'mysql:dbname=singularity;host=localhost';
$user = 'ユーザー名';
$pass = 'パスワード';

$pdo = new PDO($dsn, $user, $pass);

// 1年のうちの日ごとに処理をする
for ($i = 0; $i < 365; $i++) {
	$today = date('Y-m-d', strtotime("2014-01-01 +$i day"));
	$inArray = [];

	// 前後10日間の日付を求める
	for ($j = -10; $j <= 10; $j++) {
		$sign = ($j >= 0) ? '+' : '';
		$date = date('Y-n-j', strtotime("{$today} {$sign}{$j} day"));
		list(, $month, $day) = explode('-', $date);
		$inArray[] = "($month, $day)";
	}
	$in = implode(',', $inArray);
	// それらの日で平均、標準偏差を求める
	$rate = "sunny_days / total_days * 100";
	$select ="select AVG(sunny_rate) as avg, STD(sunny_rate) as std from summaries where (month, day) in ($in)";
	$stmt = $pdo->query($select);
	$result = $stmt->fetch(PDO::FETCH_ASSOC);
	$avg   = $result['avg']; // 平均
	$std   = $result['std']; // 標準偏差

	list(, $today_month, $today_day) = explode('-', $today);
	// z統計量を求めるために必要な、この日のデータを取得
	$z_test = "select * from summaries where month = $today_month and day = $today_day";
	$stmt = $pdo->query($z_test);
	$result = $stmt->fetch(PDO::FETCH_ASSOC);

	$rate = $result['sunny_rate']; // この日の晴れの割合

	// z 統計量の計算
	$z = ($rate - $avg) / $std;

	// データを更新する
	$update = "update summaries set avg = $avg, std = $std, z = $z where month = $today_month and day = $today_day";
	$pdo->query($update);
}