从MYSQL结果数据中获取最大值

Question

我使用MySQL从Wordpress DB返回了过去7天的一些数据，其中包含每个帖子ID的浏览量和下载量。

现在，我想打印该日期的最大下载量和最大浏览量，以及所有数据。

我的代码是：

$statquery = "
SELECT * 
  FROM wp_dstats 
 WHERE postid = $postid 
 ORDER 
    BY date ASC 
 LIMIT 7
";

$statsdata = $wpdb->get_results( $statquery );
if (count($statsdata) >= 1)
{
    // PRINT MAX DOWNLOADS AND MAX VIEWS WITH DATE HERE
    foreach($statsdata as $stats)
    {
        $views = $stats->views;
        $downloads = $stats->downloads;
        $date = $stats->date;
        echo $date.' - Views: '.$views.' | Downloads: '.$downloads,'<br />';
    }
}

根据我的要求打印所有数据，但我还想打印最大下载量和最大浏览量。

Answer 1

创建2个变量来存储最大DL和最大视图，创建另外2个变量来存储它们的日期

检查每一行的值，并在循环后打印它们。

$statquery = "SELECT * FROM wp_dstats WHERE postid = $postid ORDER BY date ASC LIMIT 7";
$statsdata = $wpdb->get_results( $statquery );

//declare vars
$max_vw = $max_dl = 0; // sorry can't remember how to declare PHP var
$max_vw_dt = $max_dl_dt = '';

if (count($statsdata) >= 1){
  foreach($statsdata as $stats){
    // CHECK AND STORE MAX DL & MAX VIEW
    if($stats->downloads > $max_dl){
      $max_dl = $stats->download;
      $max_dl_dt = $stats->date;
    }
    if($stats->views > $max_vw){
      $max_vw = $stats->views;
      $max_vw_dt = $stats->date;
    }

    // PRINT ALL RECORDS HERE    
    $views = $stats->views;
    $downloads = $stats->downloads;
    $date = $stats->date;
    echo $date.' - Views: '.$views.' | Downloads: '.$downloads.'<br />'; // you have a typo here: , -> should be .
  }
  // PRINT MAX DOWNLOADS AND MAX VIEWS WITH DATE HERE
  echo 'Max Download is '. $max_dl . ' on Date: ' . $max_dl_dt;
  echo 'Max Download is '. $max_vw . ' on Date: ' . $max_vw_dt;
}