WordPressがインストールされていない場合、WordPressデータベースから注目の画像を含む投稿を取得するにはどうすればよいですか？

最善の策は、MySQLI です。 。

<?php

$wp_database = new mysqli("yourhost", "yourusername", "yourpasssword", "yourdatabase");

/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

// Here's how you get all the posts. Adjust table names to suit.

$sql = "SELECT * FROM `wp_posts` WHERE `post_status` LIKE 'publish' AND `post_type` LIKE 'post'";

$result =  mysqli_query($wp_database, $sql);

$posts = mysqli_fetch_all($result, MYSQLI_ASSOC);
mysqli_free_result($result);
foreach ($posts as $post): ?>
<div>
    <?php print_r($post); ?>
</div>

<?php endforeach;

// And here's how you get an individual image url.

$post_id = 1181; // Your post ID here

$sql = "SELECT `guid` FROM `wp_posts` WHERE `id` IN (SELECT  `meta_value` 
FROM  `wp_postmeta` 
WHERE  `meta_key` LIKE  '_thumbnail_id'
AND  `post_id` = $post_id)";

$result = mysqli_query($wp_database, $sql);
$images = mysqli_fetch_all($result, MYSQLI_ASSOC);
mysqli_free_result($result);
foreach ($images as $image): ?>
<div>
    <?php print_r($image); ?>
</div>

<?php endforeach; ?>