在Oracle中，可以使用窗口函数和子查询来按照优先级进行分组。下面是一个示例代码：

假设我们有一个名为"orders"的表，存储了订单信息，包括订单ID、订单金额和订单优先级。

-- 创建示例表
CREATE TABLE orders (
  order_id INT,
  order_amount NUMBER,
  order_priority VARCHAR2(10)
);

-- 插入示例数据
INSERT INTO orders (order_id, order_amount, order_priority) VALUES (1, 100, 'High');
INSERT INTO orders (order_id, order_amount, order_priority) VALUES (2, 200, 'Medium');
INSERT INTO orders (order_id, order_amount, order_priority) VALUES (3, 300, 'Low');
INSERT INTO orders (order_id, order_amount, order_priority) VALUES (4, 400, 'High');
INSERT INTO orders (order_id, order_amount, order_priority) VALUES (5, 500, 'Medium');
INSERT INTO orders (order_id, order_amount, order_priority) VALUES (6, 600, 'Low');
INSERT INTO orders (order_id, order_amount, order_priority) VALUES (7, 700, 'High');
INSERT INTO orders (order_id, order_amount, order_priority) VALUES (8, 800, 'Medium');
INSERT INTO orders (order_id, order_amount, order_priority) VALUES (9, 900, 'Low');

-- 使用窗口函数和子查询按照优先级进行分组
SELECT order_id, order_amount, order_priority
FROM (
  SELECT order_id, order_amount, order_priority,
    ROW_NUMBER() OVER (PARTITION BY order_priority ORDER BY order_amount DESC) AS rn
  FROM orders
)
WHERE rn = 1;

在上面的示例中，先使用窗口函数ROW_NUMBER()对每个优先级进行排序，并为每个分组分配一个行号。然后，在子查询中，筛选出行号为1的记录，即每个优先级中金额最高的订单。