基本SQL Select语句 - 如何找到Sum？

Question

我想在表格中找到特定值的总和和数量。

在我的具体情况下，该表名为product。该表的列名称为'id，product_id，quantity和shipping_price。

该表包含:(基于SELECT * FROM product;）

product_id:1    quantity:1     end_price:15     shipping_price:1
product_id:2    quantity:2     end_price:15     shipping_price:0
product_id:1    quantity:1     end_price:15     shipping_price:1
product_id:2    quantity:1     end_price:15     shipping_price:0
product_id:1    quantity:1     end_price:15     shipping_price:1
product_id:3    quantity:1     end_price:15     shipping_price:0

我需要一个SQL语句，它将选择具有相同product_id的行数，得到quantity，end_price和shipping_price的总和。

对于此示例，我希望SQL语句返回第1项：

product_id:1    quantity:3    end_price:45    shipping_price:3

Answer 1

您可以使用SUM汇总功能，按product_id对结果进行分组。

SELECT  product_id,
        SUM(quantity) quantity,
        SUM(end_price) end_price,
        SUM(shipping_price) shipping_price
FROM    product
GROUP BY product_id

Answer 2

SELECT product_id, SUM(quantity), SUM(end_price), SUM(shipping_price) FROM product GROUP BY product_id;

Answer 3

SELECT product_id, sum(quantity), sum(end_price), sum(shipping_price) FROM product
group by product_id