Question

我有一个包含两个表，Users和Posts的数据库。我想编写一个php脚本，按顺序列出前20个用户名，其中包含他们发布的帖子数量。用户名字段是Users表中的cUsername。 Users表的intUserID字段和Posts表的intPosterID字段对应于彼此。

非常感谢任何帮助。谢谢！

Answer 1

使用GROUP BY并计数。这将为您提供其计数的用户ID列表：

SELECT intPosterId, COUNT(*)
FROM Posts
GROUP BY intPosterId
ORDER BY COUNT(*) DESC
LIMIT 20

您可以在子查询中使用结果：

SELECT u.cUsername, pcnt.postCount
FROM Users AS u
INNER JOIN (
    SELECT intPosterId, COUNT(*) as postCount
    FROM Posts
    GROUP BY intPosterId
    ORDER BY COUNT(*) DESC
    LIMIT 20
) AS pcnt
ON u.intUserId = pcnt.intPosterId

在PHP脚本中使用它：

<?php
$sql = '
    SELECT u.cUsername, pcnt.postCount
    FROM Users AS u
    INNER JOIN (
        SELECT intPosterId, COUNT(*) as postCount
        FROM Posts
        GROUP BY intPosterId
        ORDER BY COUNT(*) DESC
        LIMIT 20
    ) AS pcnt
    ON u.intUserId = pcnt.intPosterId
';
$pdo = new PDO(
    'mysql:host=your_host;dbname=your_db', 
    'username', 
    'password',
    array(PDO::ATTR_ERRMODE=>PDO::ERRMODE_EXCEPTION)
);
$stmt = $pdo->prepare($sql);
$stmt->execute();

while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
    echo "{$row['cUsername']}: {$row['postCount']} <br />\n";
}

用于列出用户总帖子的PHP脚本

1 个答案: