计算客户购买的商品的平均价格

Question

我有三个表：客户、订单和订单项。它们的设置如下：

CREATE TABLE cust_account(
cust_id DECIMAL(10) NOT NULL,
first VARCHAR(30),
last VARCHAR(30),
address VARCHAR(50),
PRIMARY KEY (cust_id));

CREATE TABLE orders(
order_num DECIMAL(10) NOT NULL,
cust_id DECIMAL(10) NOT NULL,
order_date DATE,
PRIMARY KEY (order_num));

CREATE TABLE lines(
order_num DECIMAL(10) NOT NULL,
line_id DECIMAL(10) NOT NULL,
item_num DECIMAL(10) NOT NULL,
price DECIMAL(10),
PRIMARY KEY (order_id, line_id),
FOREIGN KEY (item_id) REFERENCES products);

我需要使用 Oracle 编写一个查询，显示购买次数超过 5 次或更多次的客户的平均商品价格。这就是我一直在使用的：

SELECT DISTINCT cust_account.cust_id,cust_account.first, cust_account.last, lines.AVG(price) AS average_price
FROM cust_account
 JOIN orders
 ON cust_account.cust_id = orders.cust_id
 JOIN lines
 ON lines.order_num = orders.order_num
 WHERE lines.item_num IN (SELECT lines.item_num
    FROM lines
    JOIN orders
    ON lines.order_num = orders.order_num
        GROUP BY lines.order_num
        HAVING COUNT(DISTINCT orders.cust_id) >= 5
    );

Answer 1

我想就是这样了。我不认为它会立即起作用（我对 Oracle 一无所知）但我想你会明白的：

SELECT orders.cust_id,
       AVG(lines.price) AS average_price
FROM lines
JOIN orders ON orders.order_num = orders.order_num
WHERE orders.cust_id IN (SELECT orders.cust_id
                         FROM orders
                         GROUP BY orders.cust_id
                         HAVING COUNT(*) >= 5)
GROUP BY orders.cust_id;

子查询选择拥有超过 5 个订单的客户。主查询只获取该客户所有订单的所有行。

我想你可以使用 HAVING DISTINCT ... 来消除子查询。无论如何，带有子查询的应该可以正常工作。

UPD.

像这样

SELECT orders.cust_id,
       AVG(lines.price) AS average_price
JOIN orders ON orders.order_num = orders.order_num
GROUP BY orders.cust_id
HAVING COUNT(DISTINCT orders.id) >= 5;

Answer 2

... INNER JOIN 你所有的桌子都在一起
...GROUP BY 客户并计算每个客户线路的平均价格
...使用 HAVING 子句将结果限制为具有 5 次或更多次购买的组

查询：

SELECT   ca.first, ca.last, avg(l.price) avg_price
FROM     cust_account ca
INNER JOIN orders o ON o.cust_id = ca.cust_id
INNER JOIN lines l ON l.order_num = o.order_number
GROUP BY ca.first, ca.last
HAVING COUNT(distinct l.line_id) >=5
-- OR, maybe your requirement is ...
-- HAVING COUNT(distinct o.order_num) >= 5
-- ... the question was a bit unclear on this point

计算客户购买的商品的平均价格

Calculating average price of items purchased by customers

sql

oracle

join

subquery

where

UPD.