SQL选择不同的值，但按其他值排序 [英] SQL Select Distinct Values, but order by a different value

问题描述

我想从表中选择所有不同的order_id，然后按日期列对列表进行排序。当然，使用DISTINCT是一个查询范围的参数，因此尝试执行以下操作是不起作用的：

I want to select all distinct order_ids from my table, and order that list by the date column. Using DISTINCT is of course a query-wide parameter, so trying something like this doesn't work:

SELECT DISTINCT(orderId, datetime) 
FROM table 
ORDER BY datetime DESC

这将返回所有DISTINCT组合的orderId和datetime，所以我剩下多个我不需要的orderId。因此，我认为DISTINCT子句不是可行的方法。有人对我如何解决此问题有任何建议吗？

This returns all DISTINCT combinations of the orderId and datetime, so I'm left with multiple orderIds, which I don't want. Therefore I'm thinking that the DISTINCT clause is not the way to go. Does anyone have any suggestions on how I could solve this problem?

谢谢！

推荐答案

如果订单有多行，您要显示哪个日期？也许：

If there are multiple rows for the order, which date do you want to show? perhaps:

SELECT [orderId], MAX([datetime])
FROM [table]
GROUP BY [orderId]
ORDER BY MAX([datetime]) DESC

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