MysqL不支持窗口功能,但是您可以在SELECT
列表中使用相关子查询来精确检索一列:
SELECT
event_id,
event_type,
event_time,
(SELECT COUNT(*) FROM events EC WHERE EC.event_type = E.event_type AND EC.event_time > E.event_time) AS subsequent_event_count
FROM
events E
WHERE ...
做EXPLAIN
吧 就执行逻辑而言,这CROSS APPLY
与sql Server中的有点相似 。
另一种方法是自我加入:
SELECT
E.event_id,
E.event_type,
E.event_time,
COUNT(EC.event_id) AS subsequent_event_count
FROM
events E
LEFT JOIN events EC
ON E.event_type = EC.event_type AND E.event_type < EC.event_type
GROUP BY
E.event_id,
E.event_type,
E.event_time
您可以进行更多的创意连接,例如
EC.event_time > E.event_time AND EC.event_time < E.event_time + INTERVAL 1 DAY