MySQL查询与内部联接返回重复录入

Question

我想这个代码phpmysql

SELECT p.ID, p.post_title, p.post_name 
FROM `wp6p_popularpostsdata` AS pps 
    INNER JOIN `wp6p_posts` AS p ON pps.`postid`= p.`ID` 
WHERE p.post_type = "post" 
    AND pps.last_viewed > DATE_SUB(CURDATE(), INTERVAL 1 WEEK) 
ORDER BY pps.`pageviews` DESC 
LIMIT 4 

，并正确地给出了结果

1336Reading Between The Lines. reading-between-the-lines 
824 Benefits of Watching Anime benefits-of-watching-anime 
1427 The Day Goes By. life-goes-by 
1950 Click here if you want to be rich want-to-be-rich 

但是，当我在我的PHP文件中使用它，它返回

阅读之间的线。在线之间阅读。日子过去了。观看动画的好处

global $wpdb; 
$interval = "1 WEEK"; 
$now = current_time('mysql'); 
$top4 = $wpdb->get_results(
'SELECT p.ID, p.post_title, p.post_name 
FROM `' . $wpdb->prefix . 'popularpostssummary` AS pps 
    INNER JOIN `' . $wpdb->prefix . 'posts` AS p ON pps.`postid`= p.`ID` 
WHERE p.post_type = "post" 
    AND pps.last_viewed > DATE_SUB("' . $now . '", INTERVAL ' . $interval . ') 
ORDER BY pps.`pageviews` DESC 
LIMIT 4;', ARRAY_A 
); 
foreach($top4 AS $index => $row) { 
$class = ($index == (count($top4) - 1)) ? ' last' : ''; 
$url = get_permalink($row['ID']); 
echo '<li class="trendingPost'.$class.'">' . 
    '<a href="' . $url . '">'.$row['post_title'].'</a></li>'; 
} 

如何防止重复结果？

Answer 1

这是很有诱惑力的使用exists而不是join：

SELECT p.ID, p.post_title, p.post_name 
FROM wp6p_posts p 
WHERE p.post_type = 'post' AND 
     EXISTS (SELECT 1 
       FROM wp6p_popularpostsdata pps 
       WHERE pps.postid = p.ID AND 
        pps.last_viewed > DATE_SUB(CURDATE(), INTERVAL 1 WEEK) 
      ); 

然而，这并不让你通过pageviews订购。相反，使用聚合：

SELECT p.ID, p.post_title, p.post_name 
FROM wp6p_popularpostsdata pps INNER JOIN 
    wp6p_posts p 
    ON pps.postid = p.`ID` 
WHERE p.post_type = 'post' AND 
     pps.last_viewed > DATE_SUB(CURDATE(), INTERVAL 1 WEEK) 
GROUP BY p.ID, p.post_title, p.post_name 
ORDER BY MAX(pps.pageviews) DESC 
LIMIT 4;