wordpress根据分类关联tag-根据tag关联分类

1、根据分类关联tag，添加下面函数到function.php中

//根据分类获取该类别下的标签
function get_category_tags($args) {
    global $wpdb;
    $tags = $wpdb->get_results
    ("
        SELECT DISTINCT terms2.term_id as tag_id, terms2.name as tag_name
        FROM
            $wpdb->posts as p1
            LEFT JOIN $wpdb->term_relationships as r1 ON p1.ID = r1.object_ID
            LEFT JOIN $wpdb->term_taxonomy as t1 ON r1.term_taxonomy_id = t1.term_taxonomy_id
            LEFT JOIN $wpdb->terms as terms1 ON t1.term_id = terms1.term_id,
            $wpdb->posts as p2
            LEFT JOIN $wpdb->term_relationships as r2 ON p2.ID = r2.object_ID
            LEFT JOIN $wpdb->term_taxonomy as t2 ON r2.term_taxonomy_id = t2.term_taxonomy_id
            LEFT JOIN $wpdb->terms as terms2 ON t2.term_id = terms2.term_id
        WHERE
            t1.taxonomy = 'category' AND p1.post_status = 'publish' AND terms1.term_id IN (".$args['categories'].") AND
            t2.taxonomy = 'post_tag' AND p2.post_status = 'publish'
            AND p1.ID = p2.ID
        ORDER by tag_name
    ");
    $count = 0;
   
    if($tags) {
      foreach ($tags as $tag) {
        $mytag[$count] = get_term_by('id', $tag->tag_id, 'post_tag');
        $count++;
      }
    }
    else {
      $mytag = NULL;
    }
   
    return $mytag;
}

在需要调用的分类页上，加入下面代码 ：

$args = array( 'categories' => $catID);
			// 调用function.php中定义的函数，来获取ID为catID的分类的关联标签
			$tags = get_category_tags($args);
			// 输出我们获取到的关联标签，以列表形式打印
			$content .= "<ul>";
			if(!empty($tags)) {
			foreach ($tags as $tag) {
			$content .= "<li><a href="".get_tag_link($tag->term_id)."">".$tag->name."</a></li>";
			}
			}
			$content .= "</ul>";
			echo $content;

2、反过来，通过tag关联分类也是可以的，添加下面函数到function.php中

function get_tag_categories($args) {
    global $wpdb;
    $categories = $wpdb->get_results
    ("
        SELECT DISTINCT terms1.term_id as cat_id
        FROM
            $wpdb->posts as p1
            LEFT JOIN $wpdb->term_relationships as r1 ON p1.ID = r1.object_ID
            LEFT JOIN $wpdb->term_taxonomy as t1 ON r1.term_taxonomy_id = t1.term_taxonomy_id
            LEFT JOIN $wpdb->terms as terms1 ON t1.term_id = terms1.term_id,
            $wpdb->posts as p2
            LEFT JOIN $wpdb->term_relationships as r2 ON p2.ID = r2.object_ID
            LEFT JOIN $wpdb->term_taxonomy as t2 ON r2.term_taxonomy_id = t2.term_taxonomy_id
            LEFT JOIN $wpdb->terms as terms2 ON t2.term_id = terms2.term_id
        WHERE
            t1.taxonomy = 'category' AND p1.post_status = 'publish' AND terms2.term_id IN (".$args['tags'].") AND
            t2.taxonomy = 'post_tag' AND p2.post_status = 'publish'
            AND p1.ID = p2.ID
        ORDER by cat_id
    ");
    $count = 0;
   
    if($categories) {
      foreach ($categories as $category) {
        $mycategory[$count] = get_term_by('id', $category->cat_id, 'category');
        $count++;
      }
    }
    else {
      $mycategory = NULL;
    }
   
    return $mycategory;
}

再在分类页上加入如下代码 :

// 12,13是标签ID，多个用半角逗号隔开
$args = array( 'tags' => '12,13');
// 调用上面定义的函数，来获取ID为12，13的标签的关联分类
$categories = ludou_get_tag_categories($args);
// 输出我们获取到的关联分类，以列表形式打印
$content .= "<ul>";
if(!empty($categories)) {
  foreach ($categories as $category) {
    $content .= "<li><a href="".get_category_link( $category->term_id )."">".$category->name."</a></li>";
  }
}
$content .= "</ul>";
echo $content;