SQL：如何一起使用“ORDER BY”和“GROUP BY”？

Question

我有一个包含乘客名单和行李重量的数据库。我需要显示每个独特的乘客和行李的总重量（乘客可以携带超过1个行李）并按降序显示。

我当前无法解决的解决方案如下：

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

Answer 1

听起来你只想补偿权重：

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

Answer 2

你需要一个聚合函数来与你的GROUP BY一起使用 - 在这种情况下它将是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;