如何使 SUM() 仅对 MIN() 选择的乘客求和？

Question

我有一个关于 SQL 服务器的问题。我试图获得航班数量最少的航空公司，我还必须获得 MIN() 选择的航空公司在其航班中的乘客总数。我编写了一个代码，允许我获取航空公司的 MIN() 和 Name，但我无法以正确的方式获取总和，它总是总结所有内容。我将插入我的数据库表和我用来获取 MIN() 的代码。请记住，我不能使用显式值。

我的表：

                                             FLIGHTS
NumFlight  |       Date          | Origin |Destination|  Airline  | NumPassengers | International|
___________|_____________________|________|___________|___________|_______________|______________|
44             2014-02-08            2          3           3           135              Yes
76             2014-03-17            2          1           2            80              No
380            2014-06-04            5          1           2           147              No
421            2014-04-21            1          2           1           185              No
572            2014-09-12            5          4           3            99              Yes
906            2014-05-10            3          2           3           154              Yes
918            2014-12-24            1          5           1           122              No

           AIRLINES
   AirlineID  |   Name    |
______________|___________|
       1         Delta
       2         United
       3        Air France

             CITY
    CityID    |      City       |
______________|_________________|
      1           Chicago
      2           New York
      3           Paris
      4           Madrid
      5           Houston

我的查询:

SELECT A.Name, MINIMUM.[# of Flights] AS 'N. of Flights'
FROM AIRLINES A,
     (SELECT MIN(F.Total) AS '# of Flights' FROM 
        (SELECT Airline, COUNT(Airline) AS 'Total' FROM FLIGHTS GROUP BY Airline) F,
        AIRLINES A
    WHERE A.AirlineID = F.Airline) MINIMUM,
    (SELECT Airline, COUNT(Airline) AS 'Total' FROM FLIGHTS GROUP BY Airline) TOTAL
WHERE TOTAL.Total = MINIMUM.[# of Flights] AND A.AirlineID = TOTAL.Airline

Answer 1

您可以将 window 函数与 apply 一起使用：

select a.name, f1.Total_flights, TotalPassenger
from AIRLINES a inner join
     (select Airline, count(*) as Total_flights, 
              row_number() over (partition by Airline order by count(*)) as seq
      from FLIGHTS
      group by Airline
     ) fl
     on fl.Airline = a.AirlineID and seq = 1 cross apply
     (select sum(f.NumPassengers) as TotalPassenger
      from FLIGHTS f
      where f.Airline = f1.Airline
     ) fpassenger;

Answer 2

I have a question about SQL Server. I'm trying to get the airlines with the least number of flights

我建议使用 top (1) with ties:

select a.*, f.numflights, f.NumPassengers
from airlines a join
     (select top (1) with ties airlineid, count(*) as numflights, sum(NumPassengers) as NumPassengers
      from flights f
      group by airlineid
      order by count(*) asc
     ) f
     on f.airlineid = a.airlineid;

如何使 SUM() 仅对 MIN() 选择的乘客求和？

How do I make SUM() to only sum the passengers selected by the MIN()?

sql

sql-server

subquery