SQL：如何選擇每天每個組的最大值？

Question

比方說，我有以下幾列的表...

Name, Date, Number 

，說我們已經插入到這些列中的以下數據...

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 

現在想什麼，我要做的是獲得每個名稱的最大數值，爲每個日期。所以我的查詢結果看起來像這樣...

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 

任何幫助，將不勝感激。我使用的是SQL 2005

Answer 1

SELECT Name, `Date`, MAX(Number) 
FROM yourtable 
GROUP BY Name, `Date` 

Answer 2

什麼

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

參見：

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

Answer 3

SELECT Name, Date, MAX(Number) 
    FROM YourTable 
    GROUP BY Name, Date; 

Answer 4

這不像你想象的那麼難。

select name, date, max(number) from table group by name, date