数据库系统原理与实践——修改第三次作业

题目改了，之前应该是出错了。按照正常情况就应该是返回订单总金额。

数据库系统原理与实践/平时作业/第三次作业.tex

@@ -322,21 +322,19 @@ select cust_id, order_date from Orders natural join OrderItems where prod_id='BR
         \end{csv}
     \end{verification}
     \questionandanswer[]{
-        有一个顾客ID列表，其中包含他们已订购的总金额。OrderItems 表代表订单信息，OrderItems 表有订单号：order_num 和商品售出价格：item_price、商品数量：quantity。编写SQL语句，返回顾客 ID（Orders 表中的 cust_id），并使用子查询返回 total_ordered 每个顾客的订单总数，将结果按金额从大到小排序。
+        有一个顾客ID列表，其中包含他们已订购的总金额。OrderItems 表代表订单信息，OrderItems 表有订单号：order_num 和商品售出价格：item_price、商品数量：quantity。编写SQL语句，返回顾客 ID（Orders 表中的 cust_id），并使用子查询返回 total_ordered 每个顾客的所有订单总金额，将结果按金额从大到小排序。
 
         \includegraphics[width=0.5\linewidth]{imgs/2024-10-04-10-27-32.png}
-    }{
+    }{}
-        注意返回的是订单总数，但是要按照金额从大到小排序。
-    }
     {
         \begin{minted}{SQL}
-select cust_id, count(*) as total_ordered
+select cust_id, sum(total) as total_ordered
 from Orders
          join (select order_num, sum(item_price * quantity) as total
                from OrderItems
                group by order_num) as a on Orders.order_num = a.order_num
 group by cust_id
-order by sum(total) desc;
+order by total_ordered desc;
         \end{minted}
     }
     \begin{verification}
@@ -368,19 +366,19 @@ values ('a0001', 'cust10'),
        ('a0003', 'cust1'),
        ('a0013', 'cust2');
 
-select cust_id, count(*) as total_ordered
+select cust_id, sum(total) as total_ordered
 from Orders
          join (select order_num, sum(item_price * quantity) as total
                from OrderItems
                group by order_num) as a on Orders.order_num = a.order_num
 group by cust_id
-order by sum(total) desc;        
+order by total_ordered desc;
         \end{minted}
         \begin{csv}
 ,cust_id,total_ordered
-1,cust2,1
+1,cust2,2242
-2,cust1,2
+2,cust1,1404
-3,cust10,1
+3,cust10,1050
         \end{csv}
     \end{verification}
     \questionandanswer[]{