首先，我在查询中添加了表posmeta

function add_join_clause_to_view_sql( $join, $wpq ) {
  global $wpdb;
  if( $wpq->query[\'orderby\'] === \'price\' || $wpq->query[\'orderby\'] === \'price-desc\') {
    $post_meta_table_name = $wpdb->postmeta;
    $post_table_name = $wpdb->posts;

    $join .= "
                LEFT JOIN
                    $post_meta_table_name
                      ON $post_meta_table_name.post_id = $post_table_name.id
            ";
  }

  return $join;
}

add_filter(\'posts_join\', \'add_join_clause_to_view_sql\', 10, 2);

其次，我在WHERE语句中添加了meta\\u键

function add_where_clause_to_view_sql( $where, $wpq ) {
  global $wpdb;
  if( $wpq->query[\'orderby\'] === \'price\' || $wpq->query[\'orderby\'] === \'price-desc\') {
    $post_meta_table_name = $wpdb->postmeta;
    $where .= "
                AND
                    $post_meta_table_name.meta_key = \'_wz_currency\'
            ";
  }
  return $where;
}

add_filter( \'posts_where\' , \'add_where_clause_to_view_sql\', 10, 2 );

第三，我添加了一个带条件的计算字段

function filter_function_name_4359( $fields, $wpq ){

  global $wpdb;
  if($wpq->query[\'orderby\'] === \'price\' || $wpq->query[\'orderby\'] === \'price-desc\') {
    $post_meta_table_name = $wpdb->postmeta;
    $wc_product_meta_lookup = \'wc_product_meta_lookup\';
    $wz_currency_dollar = (int) get_option(\'wz_currency_dollar\');
    $wz_currency_euro = (int) get_option(\'wz_currency_euro\');

    $fields .= ", CAST(
CASE 
   WHEN $post_meta_table_name.meta_value = \'DOLL\' THEN $wc_product_meta_lookup.min_price * $wz_currency_dollar
   WHEN $post_meta_table_name.meta_value = \'EUR\' THEN $wc_product_meta_lookup.min_price * $wz_currency_euro
   WHEN $post_meta_table_name.meta_value = \'RUB\' THEN $wc_product_meta_lookup.min_price END AS decimal(15,2)
) AS CalculatedPrice";
  }
  return $fields;
}

add_filter( \'posts_fields\', \'filter_function_name_4359\', 10, 2 );

最后，我添加了orderby语句和calculate字段

function orderByPriceTimesCurrency($orderby, $wpq) {
  if( $wpq->query[\'orderby\'] === \'price\') {

    $orderby = \'
      CalculatedPrice ASC
    \';
  }
  if( $wpq->query[\'orderby\'] === \'price-desc\') {

    $orderby = \'
      CalculatedPrice DESC
    \';
  }


  return $orderby;
}

add_filter(\'posts_orderby_request\', \'orderByPriceTimesCurrency\', 10, 2);