使用 SQL 中的 3 个表计算收入 - 费用

Question

我正在尝试找到一种方法来编写一个简单的查询，并且在使用 Left/Right JOIN 函数时遇到了一些困难。

基本上，我想对所有出售给客户的商品 INCOME 求和 然后将所有费用相加，即支付给供应商的工资和付款（为了简单起见）

产品订单表如下所示：

╔══════════════╦════════════════╦══════════════════╗
║ order_number ║ product_number ║ product_quantity ║
╠══════════════╬════════════════╬══════════════════╣
║ 1000001      ║ 150009         ║ 50               ║
╠══════════════╬════════════════╬══════════════════╣
║ 1000002      ║ 150001         ║ 4100             ║
╠══════════════╬════════════════╬══════════════════╣
║ 1000002      ║ 150002         ║ 1200             ║
╠══════════════╬════════════════╬══════════════════╣
║ 1000002      ║ 150003         ║ 1350             ║
╠══════════════╬════════════════╬══════════════════╣
║ 1000002      ║ 150004         ║ 8200             ║
╠══════════════╬════════════════╬══════════════════╣

产品价格表如下所示：

╔════════════╦══════════════════════════════════╦═══════════════╗
║ product_id ║ product_name                     ║ product_price ║
╠════════════╬══════════════════════════════════╬═══════════════╣
║ 150001     ║ Printing Paper                   ║ 13.00         ║
╠════════════╬══════════════════════════════════╬═══════════════╣
║ 150002     ║ Coated Paper                     ║ 8.00          ║
╠════════════╬══════════════════════════════════╬═══════════════╣
║ 150003     ║ Tissue Paper                     ║ 9.00          ║
╠════════════╬══════════════════════════════════╬═══════════════╣
║ 150004     ║ Cardboard                        ║ 9.00          ║
╠════════════╬══════════════════════════════════╬═══════════════╣
║ 150005     ║ Paperboard                       ║ 7.00          ║
╠════════════╬══════════════════════════════════╬═══════════════╣
║ 150006     ║ Carton                           ║ 5.00          ║
╠════════════╬══════════════════════════════════╬═══════════════╣
║ 150007     ║ Fineart Paper                    ║ 26.00         ║
╠════════════╬══════════════════════════════════╬═══════════════╣
║ 150008     ║ Pilot Pen 0.4                    ║ 5.00          ║
╠════════════╬══════════════════════════════════╬═══════════════╣
║ 150009     ║ Stabilo Boss Highligher - Yellow ║ 4.50          ║
╚════════════╩══════════════════════════════════╩═══════════════╝

向供应商支付的款项与产品基本相同，只需从产品利润结果中扣除，并与所有员工的工资总和相结合即可。

我总共有 2 个收入表和 3 个费用表（员工、材料订单、材料价格）。

我最终的目标是：

╔══════════════╗
║ total_profit ║
╠══════════════╣
║ 2305000      ║
╚══════════════╝

产品订单：

CREATE TABLE Customer_Order_Details (
co_ID INT, #FK
p_ID INT, #FK
cod_quantity INT NOT NULL,
FOREIGN KEY (co_ID) REFERENCES Customer_Order (co_ID) ON DELETE CASCADE,
FOREIGN KEY (p_ID) REFERENCES Product (p_ID) ON DELETE CASCADE,
PRIMARY KEY (co_ID, p_ID)
);

产品价格表：

CREATE TABLE Product (
p_ID INT PRIMARY KEY,
p_name VARCHAR(80) NOT NULL,
p_price NUMERIC(10,2) 
);

---

*编辑-尝试在第一和第二表之间组合并从第三表中扣除

SELECT SUM(e.e_salary)/4 AS salary_expenses
FROM Employee AS e;

SELECT SUM(vod.vod_quantity * rm.rm_price) AS total_rm_expenses
FROM Vendor_Order_Details AS vod
JOIN Raw_Material AS rm ON rm.rm_ID = vod.rm_ID;

SELECT SUM(cod.cod_quantity * p.p_price) AS total_income
FROM Customer_Order_Details AS cod
JOIN Product AS p ON p.p_ID = cod.p_ID;

谢谢！！

Answer 1

您的问题不包括有关费用的详细信息，因此无法计算利润。但是，您可以计算收入。

例如，你可以这样做：

select sum(o.cod_quantity * p.p_price) as total_revenue
from Customer_Order_Details o
join Product p on p.p_id = o.p_id

编辑 - 计算利润：

由于您的三个查询每个都生成一行，因此您可以使用CROSS JOINs 将它们组合起来。例如：

select
  c.total_revenue - a.salary_expenses - b.total_rm_expenses as total_profit
from (
  SELECT SUM(e.e_salary)/4 AS salary_expenses
  FROM Employee
) a
cross join (
  SELECT SUM(vod.vod_quantity * rm.rm_price) AS total_rm_expenses
  FROM Vendor_Order_Details AS vod
  JOIN Raw_Material AS rm ON rm.rm_ID = vod.rm_ID
) b
cross join (
  SELECT SUM(cod.cod_quantity * p.p_price) AS total_revenue
  FROM Customer_Order_Details AS cod
  JOIN Product AS p ON p.p_ID = cod.p_ID
) c