Question

我有两个表一个CUSTOMERS

+-----------+--------------+------+-----+---------+-------+
| Field     | Type         | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| ID        | int(11)      | NO   | PRI | NULL    |       |
| FIRSTNAME | varchar(50)  | YES  |     | NULL    |       |
| LASTNAME  | varchar(50)  | YES  |     | NULL    |       |
| ADDRESS   | varchar(100) | YES  |     | NULL    |       |
+-----------+--------------+------+-----+---------+-------+

和订单

+---------------+--------------+------+-----+---------+-------+
| Field         | Type         | Null | Key | Default | Extra |
+---------------+--------------+------+-----+---------+-------+
| ID            | int(11)      | NO   | PRI | NULL    |       |
| PRODUCT_NAME  | varchar(100) | YES  |     | NULL    |       |
| PRODUCT_PRICE | double(10,4) | YES  |     | NULL    |       |
| DATE_ORDER    | date         | YES  |     | NULL    |       |
| ID_CUSTOMER   | int(11)      | YES  |     | NULL    |       |
| AMOUNT        | int(11)      | YES  |     | NULL    |       |
+---------------+--------------+------+-----+---------+-------+

我需要＆＃34;获取订单总数大于所有订单平均总和的客户的名字和姓氏。不关心重复＆＃34;。

我在这里尝试了

 select FIRSTNAME, LASTNAME, ID, 
        AVG(PRODUCT_PRICE * AMOUNT)  
 from     CUSTOMERS C 
 join     ORDERS O 
 on       C.ID = ID_CUSTOMER 
 GROUP BY FIRSTNAME, LASTNAME 
 HAVING AVG(PRODUCT_PRICE * AMOUNT) < (
                 select (PRODUCT_PRICE * AMOUNT) 
                 from ORDERS 
                 where C.ID = O.ID_CUSTOMER;

这不起作用。我需要一些帮助

Answer 1

您需要查找子查询中所有订单的平均总和。

select 
    C.ID,
    C.FIRSTNAME,
    C.LASTNAME,
    SUM(O.PRODUCT_PRICE * O.AMOUNT)
from     CUSTOMERS C 
join     ORDERS O 
on       C.ID = O.ID_CUSTOMER 
GROUP BY C.ID, C.FIRSTNAME, C.LASTNAME 
HAVING SUM(PRODUCT_PRICE * AMOUNT) > (
                 select AVG(PRODUCT_PRICE * AMOUNT)
                 from ORDERS)

Answer 2

您的代码的大部分内容都是正确的，您只需删除部分where C.ID = O.ID_CUSTOMER;即可。这不需要计算订单商品的平均价值。

使用以下代码，您可以获得所需的输出

SELECT FIRSTNAME,LASTNAME FROM CUSTOMERS 
INNER JOIN ORDERS ON CUSTOMERS.ID=ORDERS.ID_CUSTOMER 
GROUP BY CUSTOMERS.ID 
HAVING SUM(ORDERS.PRODUCT_PRICE*ORDERS.AMOUNT)>
(SELECT AVG(PRODUCT_PRICE*AMOUNT) FROM ORDERS)

使用JOIN表的MYSQL查询

2 个答案: