(转）行变列SQL语句（MSSQL）

SQL交叉表实例

很简单的一个东西，见网上好多朋友问“怎么实现交叉表？”，以下是我写的一个例子，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（用了这个很不错！）
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

不确定列，字段2的值范围不固定。

create table a
(id VARchar(4),
F2 VARCHAR(2),
F3 INT)

insert a(ID,F2,F3)
select 'A001','01',12
UNION ALL SELECT 'A001','02',24
UNION ALL SELECT 'A002','01',10
UNION ALL SELECT 'A002','03',5
UNION ALL SELECT 'A003','02',6
UNION ALL SELECT 'A004','04',13


--SELECT * FROM A


--不确定列数
declare @sql varchar(8000)
set @sql = 'select ID,'
select @sql = @sql + 'sum(case F2 when ''' +F2+'''
then F3 else '''' end) as '''+ '字段('+F2+')'','
from (select distinct F2 from A) as B
select @sql = left(@sql,len(@sql)-1) + ' from A group by ID'

--PRINT @SQL
exec(@sql)

go

==============================================================================

交叉表：

CREATE TABLE Test(字段1 VARCHAR(10),字段2 VARCHAR(10),字段3 VARCHAR(10))
INSERT Test SELECT 'a001', '01' , 12
UNION ALL SELECT 'a001', '02' , 24
UNION ALL SELECT 'a002', '01' , 10
UNION ALL SELECT 'a002', '03' , 5
UNION ALL SELECT 'a003', '02' , 6
UNION ALL SELECT 'a004', '04' , 13


SELECT * FROM Test

SELECT 字段1,
[字段(01)]=MAX(CASE WHEN 字段2 ='01' THEN 字段3 ELSE '' END),
[字段(02)]=MAX(CASE WHEN 字段2 ='02' THEN 字段3 ELSE '' END),
[字段(03)]=MAX(CASE WHEN 字段2 ='03' THEN 字段3 ELSE '' END),
[字段(04)]=MAX(CASE WHEN 字段2 ='04' THEN 字段3 ELSE '' END)
FROM Test
GROUP BY 字段1