使用group BY计算分组百分比

WITH total_sales AS (
    SELECT SUM(sales_amount) AS total_amount
    FROM sales
),
grouped_sales AS (
    SELECT category, SUM(sales_amount) AS category_sales_amount
    FROM sales
    GROUP BY category
)
SELECT 
    gs.category,
    gs.category_sales_amount,
    (gs.category_sales_amount / ts.total_amount) * 100 AS percentage
FROM grouped_sales gs, total_sales ts;

SELECT 
    COALESCE(category, 'Unknown') AS category,
    SUM(sales_amount) AS category_sales_amount
FROM sales
GROUP BY COALESCE(category, 'Unknown');

SELECT 
    gs.category,
    gs.category_sales_amount,
    CAST(gs.category_sales_amount AS DECIMAL(10, 2)) / ts.total_amount * 100 AS percentage
FROM grouped_sales gs, total_sales ts;