看这里：
// $term_slugs is a function argument: array(\'foto\', \'video\')
$term_query = "t.slug IN (\'" . implode("\',\'",$term_slugs) . "\') ";
$ids = $wpdb->get_results($wpdb->prepare("
SELECT
m.meta_value
FROM
" . $wpdb->prefix . "posts p
INNER JOIN " . $wpdb->prefix . "postmeta m ON m.post_id = p.ID
INNER JOIN " . $wpdb->prefix . "term_relationships rel ON p.ID = rel.object_id
INNER JOIN " . $wpdb->prefix . "term_taxonomy tt ON tt.term_taxonomy_id = rel.term_taxonomy_id
INNER JOIN " . $wpdb->prefix . "terms t ON tt.term_id = t.term_id
WHERE
p.post_type = \'%s\'
AND m.meta_key = \'_thumbnail_id\'
AND p.post_status = \'publish\'
AND %s
ORDER BY RAND()
LIMIT 1
",
$post_type, $term_query
));
这将写下如下内容：
WHERE
p.post_type = \'gallery\'
AND m.meta_key = \'_thumbnail_id\'
AND p.post_status = \'publish\'
AND \'t.slug IN (\\\'foto\\\',\\\'video\\\') \'
Shuold be：
WHERE
p.post_type = \'gallery\'
AND m.meta_key = \'_thumbnail_id\'
AND p.post_status = \'publish\'
AND t.slug IN (\'foto\',\'video\')
如何操作？
最合适的回答,由SO网友:Luca Reghellin 整理而成
我自己找到了答案。。
（示例代码）
$args_array = array($post_type);
$term_slugs = array(\'foto\', \'video\');
// create a string like \'%s, %s\' ecc
$placeholders = implode(\', \', array_fill(0, count($term_slugs), "%s"));
$term_query = "t.slug IN ($placeholders) ";
$args_array = array_merge($args_array, $term_slugs);
$ids = $wpdb->get_results($wpdb->prepare("
SELECT
m.meta_value
FROM
" . $wpdb->prefix . "posts p
INNER JOIN " . $wpdb->prefix . "postmeta m ON m.post_id = p.ID
INNER JOIN " . $wpdb->prefix . "term_relationships rel ON p.ID = rel.object_id
INNER JOIN " . $wpdb->prefix . "term_taxonomy tt ON tt.term_taxonomy_id = rel.term_taxonomy_id
INNER JOIN " . $wpdb->prefix . "terms t ON tt.term_id = t.term_id
WHERE
p.post_type = \'%s\'
AND m.meta_key = \'_thumbnail_id\'
AND p.post_status = \'publish\'
AND $term_query
ORDER BY RAND()
LIMIT 1
",
$args_array // pass substitutions as an array
));
