SQL：如何一起使用“ORDER BY”和“GROUP BY”？

Question

我有一個數據庫，里面有乘客名單和行李重量。 我需要顯示每個獨特的乘客和他們行李的總重量（乘客可以有超過1個行李入口）並按降序顯示。

我目前無法解決的解決方案如下：

SELECT PassengerID, Weight
FROM Baggage
GROUP BY PassengerID
ORDER BY Weight DESC;

Answer 1

聽起來你只想要衡量權重：

SELECT PassengerID, SUM(Weight) AS TotalWeight
FROM Baggage
GROUP BY PassengerID
ORDER BY SUM(Weight) DESC;

Answer 2

你需要一個聚合函數來與你的GROUP BY一起使用 - 在這種情況下它將是SUM： -

SELECT 
  PassengerID, 
  SUM(Weight)
FROM Baggage
GROUP BY PassengerID
ORDER BY SUM(Weight) DESC;

Answer 3

SELECT passenger_Name, SUM(weight) AS 'Total Weight'
FROM baggage
GROUP BY passenger_name
ORDER BY 'Total Weight' DESC;