GROUP BY 中的 ORDER BY 和 LIMIT

GROUP BY是一种用于对结果集进行分组的SQL语句。在GROUP BY语句中，可以使用ORDER BY子句对分组后的结果集进行排序，并且可以使用LIMIT子句限制结果集的数量。下面将通过自然语言生成一篇文章，介绍GROUP BY中的ORDER BY和LIMIT，并提供相应的案例代码。

sql
SELECT customer_name, order_number, order_amount
FROM orders
GROUP BY customer_name
ORDER BY order_amount DESC;

sql
SELECT customer_name, order_number, order_amount
FROM orders
GROUP BY customer_name
ORDER BY order_amount DESC
LIMIT 2;

sql
-- 建表
CREATE TABLE orders (
    order_number INT,
    customer_name VARCHAR(50),
    order_amount DECIMAL(10, 2)
);
-- 插入数据
INSERT INTO orders (order_number, customer_name, order_amount)
VALUES
    (1, 'Customer A', 100.00),
    (2, 'Customer A', 200.00),
    (3, 'Customer B', 150.00),
    (4, 'Customer B', 250.00),
    (5, 'Customer C', 300.00),
    (6, 'Customer C', 400.00);
-- 查询每个客户名对应的最高订单金额的订单
SELECT customer_name, order_number, order_amount
FROM orders
GROUP BY customer_name
ORDER BY order_amount DESC;
-- 查询每个客户名对应的最高订单金额的前两个订单
SELECT customer_name, order_number, order_amount
FROM orders
GROUP BY customer_name
ORDER BY order_amount DESC
LIMIT 2;