采用Oracle中的最大相关值

Question

我在Oracle 11g数据库中具有以下表：

CREATE TABLE travels
(
Day DATE,
Flight_Code VARCHAR2(7),
Airplane_Code VARCHAR2(7),
CONSTRAINT pk PRIMARY KEY(day,flight_code)
);

和

CREATE TABLE boardings
(
Passport VARCHAR2(7),
Day DATE,
Flight_Code VARCHAR2(7),
Luggage_Weight NUMBER(4,2),
CONSTRAINT pk PRIMARY KEY(passport,day,flight_code)
);

因此，我尝试进行查询，以查看每架飞机所运送的最大重量（Day和Flight_Code）是否为最大重量，该重量始终大于100（请注意，相同的航班，例如RY-1234-VY，可以在不同的日子进行不同的旅行，但同一天最多可以旅行一次。]

我一直在尝试类似的方法，但是它不起作用，因为它是在每次飞行后返回的，这是运输更多Luggage_Weight的那天，以及完成该任务的飞机。

SELECT Airplane_Code, Day, Flight_Code
FROM Travels
WHERE (Day, Flight_Code) IN (SELECT Day, Flight_Code
                                 FROM boardings b1
                                 GROUP BY Day, Flight_Code
                                 HAVING SUM(Luggage_Weight) = (SELECT MAX(SUM(Luggage_Weight))
                                                              FROM boardings b2
                                                              WHERE b1.Flight_Code = b2.Flight_Code
                                                              GROUP BY Day, Flight_Code
                                                              HAVING SUM(Luggage_Weight) > 100))
GROUP BY Airplane_Code, Day, Flight_Code;

Answer 1

您可以如下使用分析函数ROW_NUMBER：

SELECT Flight_Code, Airplane_Code, Day 
  FROM
    (SELECT T.Airplane_Code, T.Day, T.Flight_Code, 
           ROW_NUMBER() OVER (PARTITION BY T.Flight_Code 
                                ORDER BY B.Luggage_Weight DESC) AS RN
      FROM Travels T JOIN boardings B ON B.Flight_Code = T.Flight_Code
     WHERE B.Luggage_Weight >= 100)
 WHERE RN = 1;