SQL:如何每天为每个组选择一个最大值? [英] SQL: How to select a max value for each group per day?

问题描述

假设我有一个包含以下各列的表...

Let's say I have a table that has the following columns...

Name, Date, Number

说我们在这些列中插入了以下数据...

And say we had the following data inserted into these columns...

Bob, 2011-11-22, 1
Bob, 2011-11-22, 5
Bob, 2011-11-22, 4
Bob, 2011-11-22, 3
Wendy, 2011-11-22, 3
Wendy, 2011-11-22, 4
Wendy, 2011-11-22, 2
Wendy, 2011-11-22, 1
Chris, 2011-11-22, 4
Chris, 2011-11-22, 1
Bob, 2011-11-21, 4
Bob, 2011-11-21, 3
Wendy, 2011-11-21, 2
Wendy, 2011-11-21, 4
Wendy, 2011-11-21, 1
Chris, 2011-11-21, 4
Chris, 2011-11-21, 1

现在我想做的就是获取每个日期每个日期的最大Number值.所以我的查询结果看起来像这样...

Now what I'd like to do is get the max Number value for each Name, for each date. So my query result would look like this...

Bob, 2011-11-22, 5
Wendy, 2011-11-22, 4
Chris, 2011-11-22, 4
Bob, 2011-11-21, 4
Wendy, 2011-11-21, 4
Chris, 2011-11-21, 4

任何帮助将不胜感激.我正在使用SQL 2005.

Any help would be appreciated. I'm using SQL 2005.

推荐答案

关于

SELECT [Name], [Date], MAX(Number)
FROM [yourTable]
GROUP BY [Name], [Date] 

请参阅:

• 组(总计)函数
• MySQL GROUP BY-汇总函数

• GROUP BY (Aggregate) Functions
• MySQL GROUP BY - Aggregate Functions

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