如何解析值从wordpress$wpdb->get_results（）？

Question

我正在处理wordpress主题，未能在wpdb上使用算术运算-

若我写的是simple，那个么它会在数据库中成功更新

$sql = "SELECT room_count from " . BOOKYOURTRAVEL_ACCOMMODATION_VACANCIES_TABLE . " where accommodation_id = $accommodation_id";

    $result = $wpdb->get_results($sql) or die(mysql_error()); 


    $calc = $result;

但是如果我对结果使用减号操作，它会抛出致命的错误。

$sql = "SELECT room_count from " . BOOKYOURTRAVEL_ACCOMMODATION_VACANCIES_TABLE . " where accommodation_id = $accommodation_id";

    $result = $wpdb->get_results($sql) or die(mysql_error()); 


    $calc = $result - 1;

错误

Fatal error: Unsupported operand types in C:\xampp\htdocs\beta\wp-content\themes\byt-child\includes\post_types\accommodations.php on line 1199

朋友们，请建议我如何解决这个问题。我已经使用结果-

Answer 1

如果您期望一个结果字段，您应该使用get_var

$sql = "SELECT room_count from " . BOOKYOURTRAVEL_ACCOMMODATION_VACANCIES_TABLE . " where accommodation_id = $accommodation_id";

$result = $wpdb->get_var($sql); 

if( $result ) {
    $calc = $result - 1;
}