MySQL查詢返回多個總計列

Question

我的SQL表中有以下數據。

uid user category count date 
-------------------------------------------------- 
1  henry RED   4  2013-05-01 
2  john BLUE  3  2013-05-01 
3  alice RED   5  2013-05-01 
4  eric GREEN  2  2013-05-02 
5  eric BLUE  2  2013-05-02 
6  john RED   3  2013-05-02 
7  henry GREEN  2  2013-05-02 
8  eric RED   3  2013-05-03 
9  john BLUE  5  2013-05-03 

我想查詢，讓我回了以下數據

category 2013-05-01 2013-05-02 2013-05-03 
--------------------------------------------------- 
RED   9    3    3 
BLUE  3    2    5 
GREEN  0    4    0 

我可以用下面的查詢數據的一列，但我不知道如何多列編組爲如上所示。我想有一個查詢，我的PHP呈現，而不是循環通過每個日期。

SELECT category, SUM(count) 
FROM dbtable 
WHERE date='2013-05-01' 
GROUP BY category; 

這可能嗎？想法？

Answer 1

像這樣的東西應該工作：

SELECT 
    category, 
    SUM(CASE WHEN date = '2013-05-01' THEN count END) AS `2013-05-01`, 
    SUM(CASE WHEN date = '2013-05-02' THEN count END) AS `2013-05-02`, 
    SUM(CASE WHEN date = '2013-05-03' THEN count END) AS `2013-05-03` 
FROM dbtable 
GROUP BY category