wordpress搜索结果按标题是否包含某额外指定关键词排序

最近有个客户找模板兔二次开发主题，需求是希望在搜索页面把标题包含指定关键词（不是用户搜索词）的文章排在前面。

下面模板兔给出相应代码：

function erphp_custom_search_order($clauses, $query) {
global $wpdb;

if (!is_admin() && $query->is_search) {
$search_title_first_keyword = _MBT('search_title_first_keyword');

$clauses['orderby'] = "
CASE 
WHEN {$wpdb->posts}.post_title LIKE '%{$search_title_first_keyword}%' THEN 0 
ELSE 1 
END ASC,
{$wpdb->posts}.post_date DESC
";
}
return $clauses;
}
add_filter('posts_clauses', 'erphp_custom_search_order', 10, 2);

其中$search_title_first_keyword就是额外指定的关键词。

如果是按标题或某个文章字段包含此指定关键词：

function erphp_custom_search_order($clauses, $query) {
global $wpdb;

if (!is_admin() && $query->is_search) {
$search_title_first_keyword = _MBT('search_title_first_keyword');

$order_sql = "
CASE 
WHEN (
{$wpdb->posts}.post_title LIKE '%{$search_title_first_keyword}%' 
OR {$wpdb->postmeta}.meta_value LIKE '%{$search_title_first_keyword}%'
) THEN 0 
ELSE 1 
END ASC
";

$clauses['join'] .= " LEFT JOIN {$wpdb->postmeta} ON ({$wpdb->posts}.ID = {$wpdb->postmeta}.post_id AND {$wpdb->postmeta}.meta_key = 'erphp_search_title') ";

$clauses['orderby'] = $order_sql . ", {$wpdb->posts}.post_date DESC";

$clauses['groupby'] = "{$wpdb->posts}.ID";
}
return $clauses;
}
add_filter('posts_clauses', 'erphp_custom_search_order', 10, 2);

其中erphp_search_title是某文章字段。