mysql 分类计数求和

SELECT 
    product_category,
    COUNT(*) AS total_sales_records,
    SUM(quantity * price) AS total_sales_amount
FROM 
    sales
GROUP BY 
    product_category;

SELECT 
    COALESCE(product_category, 'Unknown') AS product_category,
    COUNT(DISTINCT id) AS total_sales_records,
    SUM(quantity * price) AS total_sales_amount
FROM 
    sales
GROUP BY 
    COALESCE(product_category, 'Unknown');

-- 创建索引
CREATE INDEX idx_product_category ON sales(product_category);

-- 分页查询
SELECT 
    product_category,
    COUNT(*) AS total_sales_records,
    SUM(quantity * price) AS total_sales_amount
FROM 
    sales
GROUP BY 
    product_category
LIMIT 10 OFFSET 0;