牛客网题目：SQL81 牛客的课程订单分析(五)

在使用 MySQL 窗口函数时一直报错不得其解：
报错：

SQL_ERROR_INFO: "You have an error in your SQL syntax; 
check the manual that corresponds to your MySQL server version 
for the right syntax to use near 'rank,\n# row_number() over 
(partition by user_id order by date) bd_r' at line 69"

直到第二天各种尝试才发现问题所在：

不可使用一些关键字作为别名

解决

将错误代码 ROW_NUMBER() OVER(PARTITION BY user_id ORDER BY date) rank

改为：row_number() over (partition by user_id order by date) bd_rk

附源原代码：

 SELECT *,
        ROW_NUMBER() OVER(PARTITION BY user_id ORDER BY date) rank,   # 错误写法（不应该直接使用rank）
#       row_number() over (partition by user_id order by date) bd_rk,   # 正确写法（或者使用'rank'）
        COUNT(product_name) OVER(PARTITION BY user_id ORDER BY date) number
FROM order_info
WHERE date > '2025-10-15' 
      AND status = 'completed'
      AND product_name IN ('C++', 'Java', 'Python')