没有完整的代码，但我知道您可以将其粘在一起。：）

查找未附加图像的所有帖子ID（借用自wp-admin/upload.php):

global $wpdb;
$lost = $wpdb->get_col( "
    SELECT ID FROM $wpdb->posts
    WHERE post_type = \'attachment\' AND post_parent > \'0\'
    AND post_parent NOT IN (
        SELECT ID FROM $wpdb->posts
        WHERE post_type NOT IN ( \'attachment\', \'" . join( "\', \'", get_post_types( array( \'public\' => false ) ) ) . "\' )
    )
" );

获取所有帖子ID的图像URL：由于这些附件没有父级，其URL等效于get_the_guid() （这是GUID看起来像URL的两个原因之一，我不喜欢这样）。

$urls = array ();
foreach ( $lost as $id )
    $urls[ $id ] = get_the_guid( $id );

现在查找带有这些图像的帖子，并将这些图像附加到这些帖子上：

global $wpdb;

foreach ( $urls as $id => $url )
{
    $posts = get_posts( array ( \'s\' => $url, \'numberposts\' => 1 ) );

    if ( ! $posts )
        continue;

    $parent_id = $posts[0]->ID;
    $wpdb->query(
        $wpdb->prepare(
            "UPDATE $wpdb->posts SET post_parent = %d WHERE post_type = \'attachment\' AND ID = %d",
            $parent_id,
            $id
        )
    );
}

未测试，仅作为提示。