MySQL查询加入最大值
简化了我的查询示例；
SELECT ce., cev. FROM calendar_event ce INNER JOIN calendar_event_viewing cev on ce.calendar_event_id = cev.calendar_event_viewing_calendar_event_id AND calendar_event_viewing_type='2' WHERE (calendar_event_viewing_public_notes='Unable to reach viewer to obtain feedback yet, will keep trying.' OR calendar_event_viewing_public_notes='Unable to reach viewer to obtain feedback yet, voicemail left, will keep trying.') ORDER BY calendar_event_start ASC 该表calendar_event_viewing可以有多个条目。我想选择最新的条目作为内部联接的一部分。最新的条目将具有的最高值calendar_event_viewing_calendar_event_id。默认情况下，如果要加入多个calendar_event_viewing行，MySQL将选择哪一行？
问题来源于stack overflow
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您可以在查询中执行子查询以仅返回最新的 calendar_event_viewing
SELECT ce., cev. FROM calendar_event ce INNER JOIN (SELECT * FROM calendar_event_viewing GROUP BY calendar_event_viewing_calendar_event_id ORDER BY id DESC) cev on ce.calendar_event_id = cev.calendar_event_viewing_calendar_event_id AND calendar_event_viewing_type='2' WHERE (calendar_event_viewing_public_notes='Unable to reach viewer to obtain feedback yet, will keep trying.' OR calendar_event_viewing_public_notes='Unable to reach viewer to obtain feedback yet, voicemail left, will keep trying.') ORDER BY calendar_event_start ASC 用id列表示最新的内容替换。
2019-11-18 11:39:53赞同 展开评论