我理解您的问题和模式，不需要cte或嵌套查询。您可以使用聚合和 having 过滤条款：

select ad.city ->> 'ru' as city,
from ticket_flights tf   
join flights as f using(flight_id)
join airports_data as ad on f.arrival_airport = ad.airport_code 
group by ad.city ->> 'ru'
having 
    max(amount) filter (where fare_conditions = 'Economy') 
    < min(amount) filter(where fare_conditions = 'Business') 
order by city

你可以重复条件句 min() 以及 max() 在 select 子句，如果要在结果集中显示它们。

对于这个groupby查询，当您将条件放入聚合时，不需要子选择。然后，您可以使用having子句轻松筛选更便宜的经济舱：

with cte_money as (
    select  
        ad.city ->> 'ru' as city,
        fare_conditions, 
        amount
    from ticket_flights tf   
    join flights as f using(flight_id)
    join airports_data as ad on f.arrival_airport = ad.airport_code 
    order by city, fare_conditions asc
    )
    select  
        city,
        max(CASE WHEN fare_conditions = 'Economy' THEN amount ELSE NULL END) as Max_Economy,
        min(CASE WHEN fare_conditions = 'Business' THEN amount ELSE NULL END) as Min_Business 
    from cte_money
    group by city, fare_conditions
    HAVING max(CASE WHEN fare_conditions = 'Economy' THEN amount ELSE NULL END) <= min(CASE WHEN fare_conditions = 'Business' THEN amount ELSE NULL END)
    order by city asc