在SQL语句中使用PHP变量

Question

我正在使用wordpress，并且我有一个SQL语句（如下所示）来收集特定类别的标记。唯一的问题是表名可能会改变（即它们不总是wp_ *）。函数$pfx = $wpdb->base_prefix;返回wordpress数据库前缀的内容。

如何在我的SQL语句中使用$pfx（而不是wp_）。

global $wpdb; 
$tags = $wpdb->get_results 
(" 
SELECT DISTINCT terms2.term_id as tag_id, terms2.name as tag_name, null as tag_link, t2.count as post_total 
    FROM 
     wp_posts as p1 
     LEFT JOIN wp_term_relationships as r1 ON p1.ID = r1.object_ID 
     LEFT JOIN wp_term_taxonomy as t1 ON r1.term_taxonomy_id = t1.term_taxonomy_id 
     LEFT JOIN wp_terms as terms1 ON t1.term_id = terms1.term_id, 

     wp_posts as p2 
     LEFT JOIN wp_term_relationships as r2 ON p2.ID = r2.object_ID 
     LEFT JOIN wp_term_taxonomy as t2 ON r2.term_taxonomy_id = t2.term_taxonomy_id 
     LEFT JOIN wp_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 post_total DESC 
"); 

谢谢。

Answer 1

变化例如

LEFT JOIN wp_term_relationships 

到

LEFT JOIN ".$pfx."term_relationships