Question

我不知道正确的语法是什么，但希望您了解我想要实现的目标：

SELECT Count(BookCategory) AS TotalBookAC
FROM Passenger
WHERE BookCategory='AC';
SELECT Count(BookCategory) AS TotalBookGen
FROM Passenger
WHERE BookCategory='General';
...

加入两个或多个sql语句需要keyword一个？

修改

乘客的表格：

TicketID - PK
TrainNumber - FK
BookDate - As Date
PassengerName - varchar
Age - num
Sex - varchar
Address - varchar
ReservationStatus - 'waiting' OR 'confirmed'
BookCategory - 'CP' OR 'General'

TrainList 的表格：

TrainNumber - PK
TrainName - varchar
Source - varchar (place)
Destination - varchar (place)
FareAC - num (currency)
FareGeneral - num (currency)
DayAvailable - varchar (weekdays)

现在我正在努力学习如何构建一个SQL语句来查询 TrainList.TrainNumber 以及 AC 的Count字段 Passenger.BookCategory 中的常规。

这是我想要实现的示例输出

+-------------+---------------+--------------+--------------+--------------+
| TrainNumber | TotalSeatsGen | TotalSeatsAC | TotalBookGen | TotalBookAC  |
+-------------+---------------+--------------+--------------+--------------+
|      1      |       10      |      12      |       11     |      13      |
+-------------+---------------+--------------+--------------+--------------+

       ^                                 . . .
    DISTINCT  <--       specific records for this TrainNumber only       -->

Answer 1

您想要从表Passenger中选择所有记录并计算出现次数。所以你必须扫描整个表并有条件地计数。在标准SQL中，您将使用CASE WHEN;在MS Access中，您使用IIF。计数用SUM完成;你每场比赛增加一个，所以你实际上在计算。

SELECT 
  TrainNumber,
  SUM( IIF(BookCategory = 'General' and ReservationStatus = 'confirmed', 1, 0) ) AS TotalSeatGen,
  SUM( IIF(BookCategory = 'AC' and ReservationStatus = 'confirmed', 1, 0) ) AS TotalSeatAC,
  SUM( IIF(BookCategory = 'General', 1, 0) ) AS TotalBookGen,
  SUM( IIF(BookCategory = 'AC', 1, 0) ) AS TotalBookAC
FROM Passenger
GROUP BY TrainNumber 
ORDER BY TrainNumber;

Answer 2

简单的答案，

声明@Passenger表（id int，BookCategory varchar（50））

插入@Passenger   值（1，＆＃39; AC＆＃39;），（2，＆＃39; AC＆＃39;），（3，＆＃39;一般＆＃39;），（4，＆＃39; AC＆＃39;） ;），（5，＆＃39;通用＆＃39;），（6，＆＃39; AC＆＃39;），（7，＆＃39; AC＆＃39），   （8，＆＃39;通用＆＃39;），（9，＆＃39; AC＆＃39）

从@Passenger中选择*

SELECT BookCategory， - Count（BookCategory）totalcount

BookCategory =＆＃39; AC＆＃39;然后Count（BookCategory）结束AS TotalBookAC，

BookCategory =＆＃39; General＆＃39;然后Count（BookCategory）结束AS TotalBookGen

FROM @Passenger

在哪里

BookCategory in（＆＃39; AC＆＃39;，＆＃39; General＆＃39;）     按BookCategory分组

选择*来自   （

SELECT BookCategory，Count（BookCategory）totalcount

- BookCategory =＆＃39; AC＆＃39;然后Count（BookCategory）结束AS TotalBookAC，

- BookCategory =＆＃39; General＆＃39;然后Count（BookCategory）结束AS TotalBookGen

FROM @Passenger

在哪里

BookCategory in（＆＃39; AC＆＃39;，＆＃39; General＆＃39;）     按BookCategory分组   ）   一个

Answer 3

SELECT BookCategory, Count(*)
FROM Passenger
GROUP BY BookCategory;

然后在应用程序的表示层中完成剩下的工作

Answer 4

为您需要的每个计数创建单独的查询。

我们假设他们将被称为qryTotalSeatsGen，qryTotalSeatsAC，qryTotalBookGen，qryTotalBookAC。

每个查询都有两个字段：TrainNumber和Total

现在使用上述所有查询创建最终查询。将他们全部加入TrainNumber，并在该字段中包含每个人的总数。

SELECT qryTotalSeatsGen.Total AS TotalSeatsGen,
 qryTotalSeatsAC.Total AS TotalSeatsAC,
 qryTotalBookGen.Total AS TotalBookGen,
 qryTotalBookAC.Total AS TotalBookAC
FROM (qryTotalSeatsGen INNER JOIN qryTotalSeatsAC ON qryTotalSeatsGen.TrainNumer = qryTotalSeatsAC.TrainNumer)
 INNERJOIN ....

使用Ms Access查询构建器（就像上面我用手写的查询只是为了给你一个想法，它可能不准确）。

Answer 5

CREATE TABLE #FinalResult
(
Tno INT,
TotSeatGen INT,
TotSeatAC INT,
TotBookGen INT,
TotBookAC INT
)

INSERT INTO #FinalResult(Tno) VALUES (1)


UPDATE #FinalResult SET TotBookAC = (SELECT Count(BookCategory) AS TotalBookAC FROM Passenger WHERE BookCategory='AC') WHERE Tno =1
UPDATE #FinalResult SET TotBookGen = (SELECT Count(BookCategory) AS TotalBookGen FROM Passenger WHERE BookCategory='General') WHERE Tno =1
............
............
............

SELECT * FROM #FinalResult

一个查询中具有不同WHERE条件的多个SELECT语句

修改

5 个答案: