SQL query help

I’m trying to run a SQL query to return an integer from the database, this is my query

$score = $wbdb->get_results("SELECT review FROM wp_gdsr_data_article WHERE post_id = {$post->ID}");

I’m guessing the issue is the $post->ID since it seems to be empty when echoed but it is used further down in other code :/

I’m pretty new to WordPress so try to avoid using jargon if possible haha ??