使用另一个表中的数据计算字段 [英] Calculated Field Using Data From Another Table

问题描述

我设置了一个表格，该表格需要一个用于计算订单价格的字段.为此，我为每个商品设置了3个字母的代码，但这些商品的价格未包含在该表中，而是包含在另一个表中.要计算价格，我需要将商品的数量乘以商品的价格.因此，基本上，我如何将3个字母的代码与另一个表中商品的价格相关联.表格中还包含3个字母的代码字段，其中包含商品的价格

I have a table set up that needs to have a field that calculates the price of an order. To do so, I have a 3-letter code set up for each item, but the price of these items isn't included in that table, but another table. To calculate the price, I need to multiply the quantity of the item by the price of the item. So basically, how do I associate the 3-letter code with the price of the item in the other table. The 3 letter code field is also included in the table with the price of the item

推荐答案

您需要的是 join :

   SELECT table1.quantity * table2.price AS result
     FROM table1
LEFT JOIN table2
       ON table1.code = table2.code

假设 table1 和 table2 具有以下字段(您可能需要根据需要进行调整):

Assuming table1 and table2 have the following fields (you might want to adjust as necessary):

• code:3个字母的代码
• quantity:一件物品的数量
• price:商品价格

• code: the 3-letter code
• quantity: the quantity of an item
• price: the price of the item

另请参阅此处以获取更多背景信息: SQL JOIN和不同类型的JOIN

Also see here for more background information: SQL JOIN and different types of JOINs

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