表现形式转换?有这样的结果表(learn表)(subject科目字段的数据为以逗号分隔的科目id)
id name code Subject
62 梁健 080A05592 1,
64 金南龙 080A05390 1,11,
97 齐立鹤 080A05402 11,12,-------------------------------------------------------------------
怎么得到这样的集合(一个科目占一条记录)
id name code Subject
62 梁健 080A05592 1,
64 金南龙 080A05390 1,
64 金南龙 080A05390 11,
97 齐立鹤 080A05402 11,
97 齐立鹤 080A05402 12,
id name code Subject
62 梁健 080A05592 1,
64 金南龙 080A05390 1,11,
97 齐立鹤 080A05402 11,12,-------------------------------------------------------------------
怎么得到这样的集合(一个科目占一条记录)
id name code Subject
62 梁健 080A05592 1,
64 金南龙 080A05390 1,
64 金南龙 080A05390 11,
97 齐立鹤 080A05402 11,
97 齐立鹤 080A05402 12,
-- Author : htl258(Tony)
-- Date : 2010-04-21 19:11:18
-- Version:Microsoft SQL Server 2008 (RTM) - 10.0.1600.22 (Intel X86)
-- Jul 9 2008 14:43:34
-- Copyright (c) 1988-2008 Microsoft Corporation
-- Developer Edition on Windows NT 5.1 <X86> (Build 2600: Service Pack 3)
--------------------------------------------------------------------------
--> 生成测试数据表:tbIF NOT OBJECT_ID('[tb]') IS NULL
DROP TABLE [tb]
GO
CREATE TABLE [tb]([id] INT,[name] NVARCHAR(10),[code] NVARCHAR(10),[Subject] NVARCHAR(10))
INSERT [tb]
SELECT 62,N'梁健','080A05592','1,' UNION ALL
SELECT 64,N'金南龙','080A05390','1,11,' UNION ALL
SELECT 97,N'齐立鹤','080A05402','11,12,'
GO
--SELECT * FROM [tb]-->SQL查询如下:
select
a.id,a.[name],[code],
[Subject]=substring(a.[Subject], b.number, charindex(',', a.[Subject], b.number) - b.number)+','
from tb a,master..spt_values b
where b.type='p'
and substring(',' + left(a.[Subject],LEN(a.[Subject])-1),b.number,1) = ','
/*
id name code Subject
----------- ---------- ---------- -----------
62 梁健 080A05592 1,
64 金南龙 080A05390 1,
64 金南龙 080A05390 11,
97 齐立鹤 080A05402 11,
97 齐立鹤 080A05402 12,(5 行受影响)
*/
无论是在sql 2000,还是在 sql 2005 中,都没有提供字符串的聚合函数,
所以,当我们在处理下列要求时,会比较麻烦:
有表tb, 如下:
id value
----- ------
1 aa
1 bb
2 aaa
2 bbb
2 ccc
需要得到结果:
id values
------ -----------
1 aa,bb
2 aaa,bbb,ccc
即, group by id, 求 value 的和(字符串相加)1. 旧的解决方法-- 1. 创建处理函数
CREATE FUNCTION dbo.f_str(@id int)
RETURNS varchar(8000)
AS
BEGIN
DECLARE @r varchar(8000)
SET @r = ''
SELECT @r = @r + ',' + value
FROM tb
WHERE id=@id
RETURN STUFF(@r, 1, 1, '')
END
GO
-- 调用函数SELECt id, values=dbo.f_str(id)
FROM tb
GROUP BY id-- 2. 新的解决方法
-- 示例数据
DECLARE @t TABLE(id int, value varchar(10))
INSERT @t SELECT 1, 'aa'
UNION ALL SELECT 1, 'bb'
UNION ALL SELECT 2, 'aaa'
UNION ALL SELECT 2, 'bbb'
UNION ALL SELECT 2, 'ccc'-- 查询处理
SELECT *
FROM(
SELECT DISTINCT
id
FROM @t
)A
OUTER APPLY(
SELECT
[values]= STUFF(REPLACE(REPLACE(
(
SELECT value FROM @t N
WHERE id = A.id
FOR XML AUTO
), '<N value="', ','), '"/>', ''), 1, 1, '')
)N/*--结果
id values
----------- ----------------
1 aa,bb
2 aaa,bbb,ccc
(2 行受影响)
--*/--各种字符串分函数--3.3.1 使用游标法进行字符串合并处理的示例。
--处理的数据
CREATE TABLE tb(col1 varchar(10),col2 int)
INSERT tb SELECT 'a',1
UNION ALL SELECT 'a',2
UNION ALL SELECT 'b',1
UNION ALL SELECT 'b',2
UNION ALL SELECT 'b',3--合并处理
--定义结果集表变量
DECLARE @t TABLE(col1 varchar(10),col2 varchar(100))--定义游标并进行合并处理
DECLARE tb CURSOR LOCAL
FOR
SELECT col1,col2 FROM tb ORDER BY col1,col2
DECLARE @col1_old varchar(10),@col1 varchar(10),@col2 int,@s varchar(100)
OPEN tb
FETCH tb INTO @col1,@col2
SELECT @col1_old=@col1,@s=''
WHILE @@FETCH_STATUS=0
BEGIN
IF @col1=@col1_old
SELECT @s=@s+','+CAST(@col2 as varchar)
ELSE
BEGIN
INSERT @t VALUES(@col1_old,STUFF(@s,1,1,''))
SELECT @s=','+CAST(@col2 as varchar),@col1_old=@col1
END
FETCH tb INTO @col1,@col2
END
INSERT @t VALUES(@col1_old,STUFF(@s,1,1,''))
CLOSE tb
DEALLOCATE tb
--显示结果并删除测试数据
SELECT * FROM @t
DROP TABLE tb
/*--结果
col1 col2
---------- -----------
a 1,2
b 1,2,3
--*/
GO
/*==============================================*/
--3.3.2 使用用户定义函数,配合SELECT处理完成字符串合并处理的示例
--处理的数据
CREATE TABLE tb(col1 varchar(10),col2 int)
INSERT tb SELECT 'a',1
UNION ALL SELECT 'a',2
UNION ALL SELECT 'b',1
UNION ALL SELECT 'b',2
UNION ALL SELECT 'b',3
GO--合并处理函数
CREATE FUNCTION dbo.f_str(@col1 varchar(10))
RETURNS varchar(100)
AS
BEGIN
DECLARE @re varchar(100)
SET @re=''
SELECT @re=@re+','+CAST(col2 as varchar)
FROM tb
WHERE col1=@col1
RETURN(STUFF(@re,1,1,''))
END
GO--调用函数
SELECT col1,col2=dbo.f_str(col1) FROM tb GROUP BY col1
--删除测试
DROP TABLE tb
DROP FUNCTION f_str
/*--结果
col1 col2
---------- -----------
a 1,2
b 1,2,3
--*/
GO/*==============================================*/
--3.3.3 使用临时表实现字符串合并处理的示例
--处理的数据
CREATE TABLE tb(col1 varchar(10),col2 int)
INSERT tb SELECT 'a',1
UNION ALL SELECT 'a',2
UNION ALL SELECT 'b',1
UNION ALL SELECT 'b',2
UNION ALL SELECT 'b',3--合并处理
SELECT col1,col2=CAST(col2 as varchar(100))
INTO #t FROM tb
ORDER BY col1,col2
DECLARE @col1 varchar(10),@col2 varchar(100)
UPDATE #t SET
@col2=CASE WHEN @col1=col1 THEN @col2+','+col2 ELSE col2 END,
@col1=col1,
col2=@col2
SELECT * FROM #t
/*--更新处理后的临时表
col1 col2
---------- -------------
a 1
a 1,2
b 1
b 1,2
b 1,2,3
--*/
--得到最终结果
SELECT col1,col2=MAX(col2) FROM #t GROUP BY col1
/*--结果
col1 col2
---------- -----------
a 1,2
b 1,2,3
--*/
--删除测试
DROP TABLE tb,#t
GO
/*==============================================*/--3.3.4.1 每组 <=2 条记录的合并
--处理的数据
CREATE TABLE tb(col1 varchar(10),col2 int)
INSERT tb SELECT 'a',1
UNION ALL SELECT 'a',2
UNION ALL SELECT 'b',1
UNION ALL SELECT 'b',2
UNION ALL SELECT 'c',3--合并处理
SELECT col1,
col2=CAST(MIN(col2) as varchar)
+CASE
WHEN COUNT(*)=1 THEN ''
ELSE ','+CAST(MAX(col2) as varchar)
END
FROM tb
GROUP BY col1
DROP TABLE tb
/*--结果
col1 col2
---------- ----------
a 1,2
b 1,2
c 3
--*/--3.3.4.2 每组 <=3 条记录的合并
--处理的数据
CREATE TABLE tb(col1 varchar(10),col2 int)
INSERT tb SELECT 'a',1
UNION ALL SELECT 'a',2
UNION ALL SELECT 'b',1
UNION ALL SELECT 'b',2
UNION ALL SELECT 'b',3
UNION ALL SELECT 'c',3--合并处理
SELECT col1,
col2=CAST(MIN(col2) as varchar)
+CASE
WHEN COUNT(*)=3 THEN ','
+CAST((SELECT col2 FROM tb WHERE col1=a.col1 AND col2 NOT IN(MAX(a.col2),MIN(a.col2))) as varchar)
ELSE ''
END
+CASE
WHEN COUNT(*)>=2 THEN ','+CAST(MAX(col2) as varchar)
ELSE ''
END
FROM tb a
GROUP BY col1
DROP TABLE tb
/*--结果
col1 col2
---------- ------------
a 1,2
b 1,2,3
c 3
--*/
GO
if not object_id('A') is null
drop table A
Go
Create table A([id] int,[cname] nvarchar(2))
Insert A
select 1,N'张三' union all
select 2,N'李四' union all
select 3,N'王五' union all
select 4,N'蔡六'
Go
--> -->
if not object_id('B') is null
drop table B
Go
Create table B([id] int,[cname] nvarchar(5))
Insert B
select 1,N'1,2,3' union all
select 2,N'3,4'
Go
create function F_str(@cname nvarchar(100))
returns nvarchar(100)
as
begin
select @cname=replace(@cname,ID,[cname]) from A where patindex('%,'+rtrim(ID)+',%',','+@cname+',')>0
return @cname
end
go
select [id],dbo.F_str([cname])[cname] from Bid cname
----------- ----------------------------------------------------------------------------------------------------
1 张三,李四,王五
2 王五,蔡六(2 個資料列受到影響)
你太利害了,你写的咱得好好看看,不知道master..spt_values 表是干啥用的
select a.[id],a.[name],a.[code],b.[Subject]
from (
select ID,[name],[code],
[Subject]=convert(xml,'<v>' + replace(left([Subject],LEN([Subject])-1), ',', '</v><v>') + '</v>') from tb
) as a
outer apply (
select [Subject] = n.v.value('.', 'varchar(10)')+',' from a.[Subject].nodes('/v') n(v)
) as b
/*
id name code Subject
----------- ---------- ---------- -----------
62 梁健 080A05592 1,
64 金南龙 080A05390 1,
64 金南龙 080A05390 11,
97 齐立鹤 080A05402 11,
97 齐立鹤 080A05402 12,(5 行受影响)
*/2005的
master..spt_values相当于master.dbo.spt_values
参考如下:
/*
标题:按某字段合并字符串之一(简单合并)
作者:爱新觉罗.毓华(十八年风雨,守得冰山雪莲花开)
时间:2008-11-06
地点:广东深圳描述:将如下形式的数据按id字段合并value字段。
id value
----- ------
1 aa
1 bb
2 aaa
2 bbb
2 ccc
需要得到结果:
id value
------ -----------
1 aa,bb
2 aaa,bbb,ccc
即:group by id, 求 value 的和(字符串相加)
*/
--1、sql2000中只能用自定义的函数解决
create table tb(id int, value varchar(10))
insert into tb values(1, 'aa')
insert into tb values(1, 'bb')
insert into tb values(2, 'aaa')
insert into tb values(2, 'bbb')
insert into tb values(2, 'ccc')
gocreate function dbo.f_str(@id int) returns varchar(100)
as
begin
declare @str varchar(1000)
set @str = ''
select @str = @str + ',' + cast(value as varchar) from tb where id = @id
set @str = right(@str , len(@str) - 1)
return @str
end
go--调用函数
select id , value = dbo.f_str(id) from tb group by iddrop function dbo.f_str
drop table tb
--2、sql2005中的方法
create table tb(id int, value varchar(10))
insert into tb values(1, 'aa')
insert into tb values(1, 'bb')
insert into tb values(2, 'aaa')
insert into tb values(2, 'bbb')
insert into tb values(2, 'ccc')
goselect id, [value] = stuff((select ',' + [value] from tb t where id = tb.id for xml path('')) , 1 , 1 , '')
from tb
group by iddrop table tb
--3、使用游标合并数据
create table tb(id int, value varchar(10))
insert into tb values(1, 'aa')
insert into tb values(1, 'bb')
insert into tb values(2, 'aaa')
insert into tb values(2, 'bbb')
insert into tb values(2, 'ccc')
go
declare @t table(id int,value varchar(100))--定义结果集表变量
--定义游标并进行合并处理
declare my_cursor cursor local for
select id , value from tb
declare @id_old int , @id int , @value varchar(10) , @s varchar(100)
open my_cursor
fetch my_cursor into @id , @value
select @id_old = @id , @s=''
while @@FETCH_STATUS = 0
begin
if @id = @id_old
select @s = @s + ',' + cast(@value as varchar)
else
begin
insert @t values(@id_old , stuff(@s,1,1,''))
select @s = ',' + cast(@value as varchar) , @id_old = @id
end
fetch my_cursor into @id , @value
END
insert @t values(@id_old , stuff(@s,1,1,''))
close my_cursor
deallocate my_cursorselect * from @t
drop table tb
参考如下:
/*
标题:数据拆分1
作者:爱新觉罗.毓华(十八年风雨,守得冰山雪莲花开)
时间:2008-11-20
地点:广东深圳
描述有表tb, 如下:
id value
----------- -----------
1 aa,bb
2 aaa,bbb,ccc
欲按id,分拆value列, 分拆后结果如下:
id value
----------- --------
1 aa
1 bb
2 aaa
2 bbb
2 ccc
*/--1. 旧的解决方法(sql server 2000)
SELECT TOP 8000 id = IDENTITY(int, 1, 1) INTO # FROM syscolumns a, syscolumns b SELECT A.id, value = SUBSTRING(A.[value], B.id, CHARINDEX(',', A.[value] + ',', B.id) - B.id)
FROM tb A, # B
WHERE SUBSTRING(',' + A.[value], B.id, 1) = ','DROP TABLE #--2. 新的解决方法(sql server 2005)
create table tb(id int,value varchar(30))
insert into tb values(1,'aa,bb')
insert into tb values(2,'aaa,bbb,ccc')
go--方法1)
SELECT A.id, B.value
FROM(
SELECT id, [value] = CONVERT(xml,'<root><v>' + REPLACE([value], ',', '</v><v>') + '</v></root>') FROM tb
)A
OUTER APPLY(
SELECT value = N.v.value('.', 'varchar(100)') FROM A.[value].nodes('/root/v') N(v)
)B--方法2)
select
a.id,b.[value]
from
(select id,[value]=convert(xml,'<root><v>'+replace([value],',','</v><v>')+'</v></root>') from tb)a
outer apply
(select [value]=C.v.value('.','nvarchar(100)') from a.[value].nodes('/root/v')C(v))b--方法3)
;with tt as
(select id,[value]=cast(left([value],charindex(',',[value]+',')-1) as nvarchar(100)),Split=cast(stuff([value]+',',1,charindex(',',[value]+','),'') as nvarchar(100)) from tb
union all
select id,[value]=cast(left(Split,charindex(',',Split)-1) as nvarchar(100)),Split= cast(stuff(Split,1,charindex(',',Split),'') as nvarchar(100)) from tt where split>''
)
select id,[value] from tt order by id option (MAXRECURSION 0)
DROP TABLE tb/*
id value
----------- ------------------------------
1 aa
1 bb
2 aaa
2 bbb
2 ccc(5 行受影响)
*/