SQL SERVER 2005中新增加了两个关系运算符 PIVOT/ UNPIVOT，能够实现表中的列转换到行，以及行到列的转换工作。
举例，还是先创建测试数据表
CREATE TABLE sales.salesByMonth
(
year char(4),
month char(3),
amount money,
PRIMARY KEY (year, month)
)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2004','Jan', 789.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2004','Feb', 389.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2004','Mar', 8867.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2004','Apr', 778.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2004','May', 78.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2004','Jun', 9.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2004','Jul', 987.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2004','Aug', 866.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2004','Sep', 7787.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2004','Oct', 85576.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2004','Nov', 855.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2004','Dec', 5878.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2005','Jan', 7.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2005','Feb', 6868.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2005','Mar', 688.0000)
INSERT INTO sales.salesByMonth (year, month, amount)
VALUES('2005','Apr', 9897.0000)
我们想要得到类似这样的结果：
Year Jan Feb Mar ..............
----- ---------- ----------- -----------
2004 789.0000 389.0000 8867.0000 .............
2005 7.0000 6868.0000 688.0000 ..............
用
上一篇文章介绍的方法当然可以实现，但现在这里想要的列是固定的，不是动态的，就是12个月，所以也可以这样子来用：
SELECT year,
SUM(case when month = 'Jan' then amount else 0 end) AS 'Jan',
SUM(case when month = 'Feb' then amount else 0 end) AS 'Feb',
SUM(case when month = 'Mar' then amount else 0 end) AS 'Mar',
SUM(case when month = 'Apr' then amount else 0 end) AS 'Apr',
SUM(case when month = 'May' then amount else 0 end) AS 'May',
SUM(case when month = 'Jun' then amount else 0 end) AS 'Jun',
SUM(case when month = 'Jul' then amount else 0 end) AS 'Jul',
SUM(case when month = 'Aug' then amount else 0 end) AS 'Aug',
SUM(case when month = 'Sep' then amount else 0 end) AS 'Sep',
SUM(case when month = 'Oct' then amount else 0 end) AS 'Oct',
SUM(case when month = 'Nov' then amount else 0 end) AS 'Nov',
SUM(case when month = 'Dec' then amount else 0 end) AS 'Dec'
FROM sales.salesByMonth
GROUP by year
但这样事实上还是相当麻烦的，现在SQLSERVER2005中有更方便的实现方法。
SELECT Year,[Jan],[Feb],[Mar],[Apr],[May],[Jun],[Jul],[Aug],[Sep],[Oct],[Nov],[Dec]
FROM (
SELECT year, amount, month
FROM sales.salesByMonth ) AS salesByMonth
PIVOT ( SUM(amount) FOR month IN
([Jan],[Feb],[Mar],[Apr],[May],[Jun],[Jul],[Aug],[Sep],[Oct],[Nov],[Dec])
) AS ourPivot
ORDER BY Year
就是这样，很简单的用法，效果是完全一样的。
我们再尝试一下把year去掉：
SELECT [Jan],[Feb],[Mar],[Apr],[May],[Jun],[Jul],[Aug],[Sep],[Oct],[Nov],[Dec]
FROM ( SELECT amount, month
FROM sales.salesByMonth ) AS salesByMonth
PIVOT ( SUM(amount) FOR month IN
([Jan],[Feb],[Mar],[Apr],[May],[Jun],[Jul],[Aug],[Sep],[Oct],[Nov],[Dec])
) AS ourPivot
得到的结果是：
Jan Feb Mar ...
---------- ------------ -----------
796.0000 7257.0000 9555.0000 ...
同一个月份的数据累加到一起。
再给个微软官方的例子：
本文转自温景良(Jason)博客园博客，原文链接：http://www.cnblogs.com/wenjl520/archive/2009/12/09/1619897.html，如需转载请自行联系原作者