Question

SELECT f.flight_id 
FROM flights f 
JOIN flightsinfo AS i ON f.flight_code = i.flight_code
JOIN airports AS a ON i.dep_airport_id = a.airport_id 
JOIN cities as c ON a.city_id = c.city_id AND city_name = 'New York'
JOIN airports AS b ON i.arr_airport_id = b.airport_id
JOIN cities AS v ON v.city_id = b.city_id AND v.city_name = 'Budapest'
HAVING f.price = MIN(price)

我正试图在两个随机城市之间以最低价格获得flight_id航班。最后一行发生错误

有子句
中的未知列

当我尝试使用where / from error时：

无效使用群组功能。

有什么想法吗？

Answer 1

如果您需要基于订单的第一条记录，只需使用SELECT TOP 1或TAKE 1，具体取决于rdbms，并按您需要订购的字段排序。

SQL SERVER 2008

SELECT TOP 1
    f.flight_id
FROM
    flights f
    JOIN flightsinfo AS i ON f.flight_code = i.flight_code
    JOIN airports AS a ON i.dep_airport_id = a.airport_id
    JOIN cities AS c ON a.city_id = c.city_id
                        AND city_name = 'New York'
    JOIN airports AS b ON i.arr_airport_id = b.airport_id
    JOIN cities AS v ON v.city_id = b.city_id
                        AND v.city_name = 'Budapest'
ORDER BY 
    f.price

<强>的MySQL

SELECT 
    f.flight_id
FROM
    flights AS f
    JOIN flightsinfo AS i ON f.flight_code = i.flight_code
    JOIN airports AS a ON i.dep_airport_id = a.airport_id
    JOIN cities AS c ON a.city_id = c.city_id
                        AND city_name = 'New York'
    JOIN airports AS b ON i.arr_airport_id = b.airport_id
    JOIN cities AS v ON v.city_id = b.city_id
                        AND v.city_name = 'Budapest'
ORDER BY 
    f.price
LIMIT 1;

Answer 2

使用公用表格表达式（cte）查找价格最低的航班。（如果它是平局，将返回两个航班。）

WITH CTE (flight_id, price) AS
(
SELECT f.flight_id, f.price
FROM flights f 
JOIN flightsinfo AS i ON f.flight_code = i.flight_code
JOIN airports AS a ON i.dep_airport_id = a.airport_id 
JOIN cities as c ON a.city_id = c.city_id AND city_name = 'New York'
JOIN airports AS b ON i.arr_airport_id = b.airport_id
JOIN cities AS v ON v.city_id = b.city_id AND v.city_name = 'Budapest'
)
select flight_id, price
from cte
where price = (select min(price) from cte)

或者，JamieD77的ANSI SQL版本回答：

SELECT 
    f.flight_id
FROM
    flights AS f
    JOIN flightsinfo AS i ON f.flight_code = i.flight_code
    JOIN airports AS a ON i.dep_airport_id = a.airport_id
    JOIN cities AS c ON a.city_id = c.city_id
                        AND city_name = 'New York'
    JOIN airports AS b ON i.arr_airport_id = b.airport_id
    JOIN cities AS v ON v.city_id = b.city_id
                        AND v.city_name = 'Budapest'
ORDER BY 
    f.price
FETCH FIRST 1 ROW WITH TIES

WITH TIES表示如果它是平局就会返回多行！

SQL选择错误

2 个答案: