基本SQL Select语句 - 如何查找总和？

Question

我想查找我的表中特定值的总数和计数。

在我的具体情况下，该表被称为product。该表的列名是'id,product_id,quantity和shipping_price。

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，将选择行的量与同product_id，得到的quantity，end_price和shipping_price的总和。

对于这个例子，我想SQL语句的回报，为项目1：

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

Answer 1

可以使用SUM聚合函数，通过product_id分组结果。

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;