使用WP_Query 使用tax_query 和ameta_query 参数，并仅返回ID以节省一点服务器资源。

$args = array(
  \'post_type\' => \'post\',
  \'tax_query\' => array(
    array(
      \'taxonomy\' => \'people\',
      \'field\'    => \'slug\',
      \'terms\'    => \'bob\',
    ),
  ),
  \'meta_query\' => array(
    array(
      \'key\'     => \'age\',
      \'value\'   => array( 3, 4 ),
      \'compare\' => \'IN\',
    ),
  ),
  \'fields\' => \'ids\'.
);
$query = new WP_Query( $args );