题解 | #排序,如果城市为空，则按国家排序#
请按城市对客户进行排序,如果城市为空，则按国家排序
https://www.nowcoder.com/practice/c1b1d5bd008b4797ab2ef53a3afc4aba
select
*
from customers_info
order by
(
case
when city is not null
then city
else country
end
)
