你可能很困惑 ORDER BY 以及 HAVING .
仅显示至少租用了一部电影的国家。
这就是你要做的：

order by rental_count >=1

但要对聚合列进行筛选，应使用having子句：

having rental_count >=1

但是，您可以通过使用 INNER JOIN 而不是 LEFT OUTER JOIN . 那么在这种情况下就不需要having子句了。
ORDERBY子句用于按特定顺序获取结果。如果希望按字母顺序对国家进行排序，可以使用

order by e.country

我猜您是想按国家名称acc\ U account\ U transactions对结果进行排序，而不是按计数

order by e.country

use upgrad;
select Country, count(rental_id) as Rental_count
from rental
inner join customer
using (customer_id)
inner join address
using (address_id)
inner join city
using (city_id)
inner join country
using (country_id)
group by country
order by country;

select country,count(rental_id) from country
inner join city using (country_id)
inner join address using (city_id)
inner join customer using (address_id)
inner join rental using (customer_id)
group by country
having count(rental_id)>0
order by country asc;

select country, count(rental_id>=1) as rental_count
from rental
join customer using (customer_id)
join address using (address_id)
join city using (city_id)
join country using (country_id)
group by country
order by country desc;