php - 避免使用双 GROUP BY sql 语句的 PHP 解决方法

Question

我想对计数的分组结果进行 SQL 查询。我能够做到这一点的唯一方法是在 PHP 的帮助下。但我确信可以通过一条 SQL 语句来完成此操作。

该表的结构如下: id、user_hash、时间戳

我的 PHP 小解决方法如下所示:

$sql = 'SELECT count(id) AS \'total clicks\' FROM stats WHERE timestamp > UNIX_TIMESTAMP(NOW() - INTERVAL '.$num_days.' DAY) GROUP BY user_hash ORDER BY count(id) DESC';
$result = $mysqli->query($sql);
$count = array();
while ($row = mysqli_fetch_assoc($result)) {
    if (isset($count[$row['total clicks']])) {
        $count[$row['total clicks']]++;
    } else {
        $count[$row['total clicks']] = 1;
    }
}

foreach ($count as $k => $v) {
    echo $v." users clicked ".$k." times\n";
}

我可能会惊叹它是多么容易，但我似乎无法获得一个一体化的 SQL 解决方案。 :)

Answer 1

请尝试:

$sql = 'SELECT
    A.`user_times_clicked`,
    COUNT(A.user_hash) AS `user_count`
FROM(
    SELECT 
        count(id) AS `user_times_clicked`,
        user_hash   
    FROM 
        stats 
    WHERE 
        timestamp > UNIX_TIMESTAMP(NOW() - INTERVAL '.$num_days.' DAY) 
    GROUP BY 
        user_hash 
    ) AS A
GROUP BY    
    A.`user_times_clicked`
ORDER BY 
    COUNT(A.user_hash) DESC'

希望对您有所帮助。