Question

我正在使用MySql中的影院预订系统（我的第一个SQL项目）。我有三张桌子：

Production (contains Title, BasicTicketPrice), 
Performance (PerformanceDate, PerformanceTime, Title) 
Booking (Email of person who booked, PerformanceDate, PerformanceTime, RowNumber).

每个人都预订了两到三场演出门票（使用他们的电子邮件预订）。

我需要写一个查询，显示所有预订座位的价格，我需要输出RowNumber，预订人的电子邮件和计算价格。

我知道我需要加入这些表并使查询显示一个名为Calculated Price的临时列，但我不知道如何计算价格。

我试过了：

SELECT DISTINCT b.RowNumber, b.Email, pr.BasicTicketPrice 
FROM booking b, production pr performance p
WHERE p.Title=b.PerfDate*b.PerfTime*b.RowNumber;

SELECT CONCAT (PerfDate, PerfTime, RowNumber) AS BookingID FROM booking;

SELECT RowNumber, Email, CONCAT(PerfDate, PerfTime, RowNumber) AS BookingID FROM booking;

SELECT RowNumber, Email, CONCAT((CONCAT(PerfDate, PerfTime, RowNumber) AS BookingID 
   FROM booking)BasicTicketPrice*BookingID);

SELECT RowNumber, Email, CONCAT(PerfDate, PerfTime, RowNumber) AS BookingID INTEGER 
FROM booking;

SELECT RowNumber FROM booking
LEFT JOIN (SELECT Title FROM performance WHERE '2017-11-01 19:00:00' Email IS NULL);

但它没有用。

有什么建议吗？我会感激任何想法。

Answer 1

假设：

每预订座位预订一行
Title是Production
PerformanceDate, PerformanceTime是Performance

您将根据上面假设的键将三个表连接在一起。您似乎希望按预订门票的人将预订分组在一起 - 如果是这样，您需要使用汇总来显示座位号（我使用GROUP_CONCAT来划分它们），以及COUNT购买的门票，并乘以门票费用。

SELECT 
   b.Email, prod.Title, per.PerformanceDate, per.PerformanceTime, 
   GROUP_CONCAT(RowNumber) AS BookedSeats, 
   COUNT(RowNumber) * prod.BasicTicketPrice AS TotalCost
FROM Booking b
INNER JOIN Performance per  
     ON b.PerformanceDate = per.PerformanceDate 
        AND b.PerformanceTime = per.PerformanceTime
INNER JOIN Production prod
     ON per.Title = prod.Title
GROUP BY 
   b.Email, prod.Title, per.PerformanceDate, per.PerformanceTime, prod.BasicTicketPrice
ORDER BY prod.Title, per.PerformanceDate, per.PerformanceTime;

从技术上讲，我们应该在GROUP BY中包含所有非聚合列，因此也会列出prod.BasicTicketPrice。

从3个不同的表中确定每个用户的总成本

1 个答案: