Question

我试图制定一个SQL查询来计算人数的差异＆＃34;到达＆＃34;和＃34;离开＆＃34;按城市和日期分组。

TravelerID    ArrivalDate     DepartureDate         City
   1           2015-10-01        2015-10-03       New York
   2           2015-10-02        2015-10-03       New York
   3           2015-10-02        2015-10-04       Chicago
   4           2015-10-01        2015-10-02       Chicago

我希望得到一张看起来像

的桌子

NumOfTravelers     Date        City
     1           2015-10-01    New York
     1           2015-10-02    New York
     -2          2015-10-03    New York
     1           2015-10-01    Chicago
     0           2015-10-02    Chicago
     -1          2015-10-04    Chicago

NumOfTravelers的正数表示在该特定日期有更多人抵达该城市。 NumOfTravelers的负数表示在该特定日期有更多人离开该城市。

在尝试分解此SQL查询时，我已尝试

SELECT COUNT(TravelerID) as NumTravelersArrivng, ArrivalDate, City FROM TravelTable GROUP BY ArrivalDate, City;


SELECT COUNT(TravelerID) as NumTravelersDeparting, DepartureDate, City FROM TravelTable GROUP BY DepartureDate, City;

我试图获得＆＃34; NumTravelersArriving＆＃34; - ＆＃34; NumTravelersDeparting＆＃34;到表示＆＃34;旅行者吞吐量的列中＃34;按城市和日期分组。

我对此感到非常难过。我正在使用SQL Server，并且在使用表别名和列别名时遇到了令人沮丧的时间。

Answer 1

试试这个：

SELECT * 
FROM (
    SELECT City, ArrivalDate As Date, COUNT(TravelerID) As NumOfTravelers
    FROM TravelTable 
    GROUP BY City, ArrivalDate
) a
FULL JOIN (
    SELECT City, DepartureDate As Date, COUNT(TravelerID) * -1 As NumOfTravelers
    FROM TravelTable
    GROUP BY City, DepartureDate 
) b ON b.City = a.City AND b.Date = a.Date

用于计算吞吐量的SQL查询＆＃34;减去＆＃34;两个使用Group By的Select语句

1 个答案: