GROUP BY SQL Server 后的总和百分比

SQL Server中使用GROUP BY实现总和百分比

sql
CREATE TABLE sales (
  product_name VARCHAR(50),
  sales_amount DECIMAL(10, 2),
  sales_date DATE
);
INSERT INTO sales (product_name, sales_amount, sales_date)
VALUES ('产品A', 1000, '2021-01-01'),
       ('产品A', 2000, '2021-01-02'),
       ('产品B', 1500, '2021-01-01'),
       ('产品B', 2500, '2021-01-02'),
       ('产品C', 500, '2021-01-01'),
       ('产品C', 1000, '2021-01-02');

sql
SELECT product_name, SUM(sales_amount) AS total_sales
FROM sales
GROUP BY product_name;

product_name | total_sales
-------------|------------
产品A        | 3000
产品B        | 4000
产品C        | 1500

sql
SELECT product_name, 
       SUM(sales_amount) AS total_sales,
       (SUM(sales_amount) / (SELECT SUM(sales_amount) FROM sales)) * 100 AS sales_percentage
FROM sales
GROUP BY product_name;

product_name | total_sales | sales_percentage
-------------|-------------|-----------------
产品A        | 3000        | 37.5
产品B        | 4000        | 50
产品C        | 1500        | 18.75