我正在尝试计算每个客户的订单之间的平均时间。我有一个客户表和订单表(fk key customerid)。但是,以下 SQL 代码未编译。我收到的错误消息如下:此处不允许使用窗口函数。
这是我的代码:
SELECT customer.customerid, AVG(DATEDIFF(orders.orderdate, LAG(orders.orderdate) OVER (PARTITION BY orders.customerid ORDER BY orders.orderdate))) AS avg_time_between_orders
FROM customer
JOIN orders ON customer.customerid = orders.customerid
GROUP BY customerid;