SQL交叉表实例简要说明

很简单的一个东西，见网上好多朋友问“怎么实现交叉表？”，以下是我引用一个CSDN论坛上例子，数据库基于SQL SERVER 2000。
-- ======================================================
--交叉表实例
-- ======================================================
建表：
在查询分析器里运行：
CREATE TABLE [Test] (
       [id] [int] IDENTITY (1, 1) NOT NULL ,
       [name] [nvarchar] (50) COLLATE Chinese_PRC_CI_AS NULL ,
       [subject] [nvarchar] (50) COLLATE Chinese_PRC_CI_AS NULL ,
       [Source] [numeric](18, 0) NULL
) ON [PRIMARY]
GO
INSERT INTO [test] ([name],[subject],[Source]) values (N'张三',N'语文',60)
INSERT INTO [test] ([name],[subject],[Source]) values (N'李四',N'数学',70)
INSERT INTO [test] ([name],[subject],[Source]) values (N'王五',N'英语',80)
INSERT INTO [test] ([name],[subject],[Source]) values (N'王五',N'数学',75)
INSERT INTO [test] ([name],[subject],[Source]) values (N'王五',N'语文',57)
INSERT INTO [test] ([name],[subject],[Source]) values (N'李四',N'语文',80)
INSERT INTO [test] ([name],[subject],[Source]) values (N'张三',N'英语',100)
Go
 

交叉表语句的实现：
--用于：交叉表的列数是确定的
select name,sum(case subject when '数学' then source else 0 end) as '数学',
          sum(case subject when '英语' then source else 0 end) as '英语',
           sum(case subject when '语文' then source else 0 end) as '语文'
from test
group by name
 
 
--用于：交叉表的列数是不确定的
declare @sql varchar(8000)
set @sql = 'select name,'
 
select @sql = @sql + 'sum(case subject when '''+subject+'''
                          then source else 0 end) as '''+subject+''','
 from (select distinct subject from test) as a
 
select @sql = left(@sql,len(@sql)-1) + ' from test group by name'
exec(@sql)
go