sql - Mariadb:在 WHERE 子句中使用窗口函数 LAG 的结果

Question

我使用以下查询来获取两个时间戳之间的差异:

SELECT tracker_id,
       TIMESTAMP,
       LAG(TIMESTAMP) OVER(ORDER BY TIMESTAMP DESC),
       TIMESTAMPDIFF(MINUTE,
                     TIMESTAMP,
                     LAG(TIMESTAMP) OVER(ORDER BY TIMESTAMP DESC)) AS diff_in_minutes
  FROM comm_telemetry
 WHERE comm_telemetry.tracker_id = "123456789"
 ORDER BY comm_telemetry.timestamp DESC;

我想过滤结果，仅在 diff_in_months > 0 时显示。问题是，WHERE 子句中不允许使用 Windows 函数。

有什么建议可以解决这个问题吗？

Answer 1

您需要首先计算子查询中的滞后，然后再次查询以使用它进行过滤。

WITH cte AS (
    SELECT tracker_id,
           TIMESTAMP,
           TIMESTAMPDIFF(MINUTE,
                         TIMESTAMP,
                         LAG(TIMESTAMP) OVER (ORDER BY TIMESTAMP DESC)) AS diff_in_minutes 
    FROM comm_telemetry 
    WHERE tracker_id = '123456789'
)

SELECT tracker_id, TIMESTAMP, diff_in_minutes
FROM cte
WHERE diff_in_minutes > 0
ORDER BY TIMESTAMP DESC;