最好的解決方法是編寫自定義SQL查詢並一次獲取所有標籤。任何其他使用WP核心函數的方法都會產生大量的小型SQL查詢,這是多餘的。
使用此查詢來獲取所有類別標籤:
SELECT DISTINCT pt.term_id, pt.name
FROM wp_terms AS t
LEFT JOIN wp_term_taxonomy AS tt ON tt.term_id = t.term_id
LEFT JOIN wp_term_relationships AS tr ON tr.term_taxonomy_id = tt.term_taxonomy_id
LEFT JOIN wp_term_relationships AS ptr ON ptr.object_id = tr.object_id AND ptr.term_taxonomy_id <> tr.term_taxonomy_id
LEFT JOIN wp_term_taxonomy AS ptt ON ptt.term_taxonomy_id = ptr.term_taxonomy_id AND ptt.taxonomy = 'post_tag'
LEFT JOIN wp_terms AS pt ON pt.term_id = ptt.term_id
WHERE t.name = 'Car' AND tt.taxonomy = 'category' AND pt.term_id IS NOT NULL
ORDER BY pt.term_id