MYSQL將聯接轉換為子查詢

Question

我試圖將聯接查詢轉換為不具有聯接，而僅使用子查詢，但是對我而言，我不知道一種方法。

表格：

使用這些表，我嘗試執行以下操作：使用子查詢獲取注冊費用最高的與會者的名字，姓氏和注冊費用。

該查詢使用聯接產生該結果。

SELECT FirstName, LastName, SUM(tblregistration.RegistrationPaid) AS `AmountPaid`
FROM tblregistration, tblattendees
WHERE tblregistration.AttendeeID = tblattendees.AttendeeID
GROUP BY tblregistration.AttendeeID 
ORDER BY `AmountPaid` DESC 
LIMIT 5

有沒有辦法做到這一點？ 謝謝。

Answer 1

這應該工作：

SELECT
  (SELECT FirstName FROM tblattendees WHERE tblregistration.AttendeeID = tblattendees.AttendeeID) AS `FirstName`,
  (SELECT LastName FROM tblattendees WHERE tblregistration.AttendeeID = tblattendees.AttendeeID) AS `LastName`,
  SUM(tblregistration.RegistrationPaid) AS `AmountPaid`
FROM tblregistration
GROUP BY tblregistration.AttendeeID
ORDER BY `AmountPaid` DESC
LIMIT 5