[英]SQL - Get the latest event from table
I got two tables. 我有两张桌子。
A dealer table (id, name, etc.) and an event table (id, did(dealerid), eid(fb eventid), venue, etc.) where I save the dealerid, eventid, eventurl and date from facebook. 经销商表(id,名称等)和事件表(id,did(dealerid),eid(fb eventid),场所等),我从Facebook保存了Dealerid,eventid,eventurl和日期。
I can get all data with this sql statement: 我可以使用以下sql语句获取所有数据:
SELECT * FROM dealer as t_d INNER JOIN events AS t_e
ON t_d.id = t_e.did;
This works fine. 这很好。
1 Laden Dortmund Stra 12 45525 Dortmund DE www.google.de 0201-123456 laden@dortmund.de 300 400 1 1 416364098428245 https://www.facebook.com/events/416364098428245/ 2013-01-28
2 Laden Unna Wurststr. 123 45130 Unna DE www.bing.de 0222-11223344 laden@unna.de 400 276 2 2 145457548940302 https://www.facebook.com/events/145457548940302/ 2013-03-08
2 Laden Unna Wurststr. 123 45130 Unna DE www.bing.de 0222-11223344 laden@unna.de 400 276 3 2 405092472902921 https://www.facebook.com/events/405092472902921/ 2013-04-26
As you can see, I get two rows for the dealer id 2, because there are two events listed. 如您所见,由于有两个事件,我得到了两行作为经销商ID 2的信息。
How can I get the event, which is the closest to this date (today). 我如何获得该活动,它是距该日期(今天)最近的事件。
Later, there will be like 20 Dealer and for each one at least 3-4 events. 以后,将有20个发牌人,每一个至少有3-4个事件。
A hint would be nice, thank you! 提示会很好,谢谢!
UPDATE: 更新:
This is the solution! 这是解决方案!
SELECT t_d.*, t_e.*, DATE_FORMAT(t_e.date,'%d.%m.%Y') as date
FROM dealer as t_d
INNER JOIN events AS t_e
ON t_d.id = t_e.did
INNER JOIN
(
SELECT did, MIN(date) minDate
FROM events
GROUP BY did
) e ON t_e.did = e.did AND
t_e.date = e.minDate
But is it somehow possible to display ALL dealers, even if no event exists for the dealer? 但是,即使没有针对经销商的活动,也可以通过某种方式显示所有经销商吗?
SELECT t_d.*, t_e.*
FROM dealer as t_d
INNER JOIN events AS t_e
ON t_d.id = t_e.did
INNER JOIN
(
SELECT did, MAX(date) maxDate
FROM events
GROUP BY did
) e ON t_e.did = e.did AND
t_e.date = e.maxDate
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