我有一个Access数据库,每天都在获取新数据.每组数据包含几个类别,每个类别可能有0个或许多记录.
I have an Access database that is getting new data on a daily basis. Each set of data contains several categories and each category may have 0 or many records.
每天,我都会将此数据附加到数据库中,并附加一列今天的日期.因此,同一记录可能会存在多天.
Every day I will append this data to the database with an additional column for today's date. Therefore, same record may exist across multiple days.
例如,我所包含的列可能包括:
For example, the columns I have may include:
- 类别
- Detail1
- Detail2
- ...
- Report_Date
我需要从该数据库中获得的是每个类别下的最新详细信息.
What I need to get from this database is the latest details under each category.
我遇到的一些问题
除了每个单独的类别,UNION还能通过SQL做到这一点吗?
Is there any good way I can do this by SQL besides UNION every single category up?
预先感谢您的帮助.
推荐答案我刚刚弄清楚了.我可以使用子查询来做到这一点.
I just figured it out. I can use a subquery to do this.
在这里.
SELECT * FROM my_table AS T1 WHERE T1.report_date = (SELECT MAX(report_date) FROM my_table AS T2 WHERE T1.category = T2.category)更多推荐
MS Access SQL获取每个类别的最新记录
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