Question

我想在查询中输入不同表中两列之间的减法，它一直在说错误......

SELECT FlightDate,
       Plane, 
       Destination,
       Capacity
FROM  
       FlightSchedule, 
       Routes, 
       Aircrafts
WHERE 
       FlightSchedule.RID=Routes.RouteID 
       AND FlightSchedule.Plane=Aircrafts.AcID 
       AND (SELECT SUM(Capacity) 
            FROM Aircrafts) 
            - 
           (SELECT Class , count(*) 
           FROM Tickets);

Answer 1

多个级别的查询错误。

首先，您不能将SELECT容量的详细信息作为WHERE下的子查询。 WHERE子句用于条件参数。

试试这个：

WITH VACANCY as (SELECT SUM(Capacity) FROM Aircrafts) - (SELECT Count(*) FROM Tickets) 
SELECT FlightDate,Plane, Destination, Vacancy
FROM FlightSchedule,Routes,Aircrafts
WHERE  FlightSchedule.RID=Routes.RouteID AND FlightSchedule.Plane=Aircrafts.AcID;

你还需要一个条件选择票数，但我不知道票的架构所以......

Answer 2

我会把它分成两部分。首先获取所需的数据，然后执行数学运算。您还使用旧的SQL语法。您应该使用新的JOIN语法重新格式化。它也更容易阅读。

1宣布一张表格，为您提供航班时刻表和飞机信息。

Declare @AIRCRAFTCAPACITY Table
(
    [FlightDate] [datetime] NOT NULL,
    [Plane] [varchar](50) NOT NULL,
    [Destination] [varchar](50) NOT NULL,
    [Capacity] [INT] NOT NULL,
    [NoOfSeatsRemaining] [INT] NULL
);

然后插入您需要的数据。

INSERT @AIRCRAFTCAPACITY
(
    [FlightDate],
    [Plane],
    [Destination],
    [Capacity]
)
SELECT  FS.FlightDate,
        A.Plane, 
        FS.Destination,
        A.Capacity
FROM 
        FlightSchedule FS
INNER
JOIN    Routes R
ON
        FS.RID = R.RouteID
INNER
JOIN    Aircrafts A
ON
        FS.Plane = A.AcID

现在执行数学计算剩余容量。我已假设您正在为特定路线执行此操作。但我相信你可以相应地调整你的SQL。

UPDATE  @AIRCRAFTCAPACITY
SET
        [NoOfSeatsRemaining] = [Capacity] - T.TICKETS_SOLD
FROM
        @AIRCRAFTCAPACITY A
INNER
JOIN    
        (
            SELECT ROUTEID, COUNT(ROUTEID) AS TICKETS_SOLD
            FROM
                   Tickets T1
            WHERE
                   T1.ROUTEID = A.ROUTEID
            GROUP
            BY     ROUTEID
        ) T
ON
        A.ROUTEID = T.ROUTEID

Apolgies如果语法稍微偏离，因为当你没有基础表时很难构造SQL。

但希望它会有所帮助。

如何在SQL中的不同表中减去两列

2 个答案: