请问:怎样通过一句SQL,按一个字段分组,把另一个字段串联起来?
(不要用游标)表结构如下:
Tno ColA
----- ----------
001 A
001 B
001 C
001 D
001 E
002 A
002 C
002 D
002 E
002 G
003 A
003 C
004 B
004 F
004 I我想得到的结果:
001 ABCDE
002 ACDEG
003 AC
004 BFK
(不要用游标)表结构如下:
Tno ColA
----- ----------
001 A
001 B
001 C
001 D
001 E
002 A
002 C
002 D
002 E
002 G
003 A
003 C
004 B
004 F
004 I我想得到的结果:
001 ABCDE
002 ACDEG
003 AC
004 BFK
--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
returns varchar(100)
as
begin
declare @sql varchar(100)
select @sql=isnull(@sql+'','')+ColA from [Table] where Tno=@Tno
return @sql
end
go
select Tno,dbo.test(Tno) from [Table] group by Tno
--创建合并函数:
create function f_wsp(@tno varchar(10))
returns varchar(1000)
as
begin
declare @sql varchar(1000)
select @sql=isnull(@sql+',','')+cola from 表名 where tno=@tno
return @sql
end--调用函数:
select distinct tno,cola=dbo.f_wsp(tno) from 表名
if object_id('tempdb.dbo.T') is not null drop table T
create table T (Tno varchar(3),ColA varchar(1))
insert into T
select '001','A' union all
select '001','B' union all
select '001','C' union all
select '001','D' union all
select '001','E' union all
select '002','A' union all
select '002','C' union all
select '002','D' union all
select '002','E' union all
select '002','G' union all
select '003','A' union all
select '003','C' union all
select '004','B' union all
select '004','F' union all
select '004','I'
GO--合并处理函数
CREATE FUNCTION dbo.f_str(@Tno varchar(3))
RETURNS varchar(100)
AS
BEGIN
DECLARE @re varchar(100)
SET @re=''
SELECT @re=@re+ColA
FROM T
WHERE Tno=@Tno
RETURN(@re)
END
GOselect distinct Tno,dbo.f_str(Tno) ColA
from T
godrop table T
drop function dbo.f_str/*
Tno ColA
---- ----------------------------------------------------------------------------------------------------
001 ABCDE
002 ACDEG
003 AC
004 BFI(4 row(s) affected)*/
/******************************************************************************/
/*回复:20080526001总:00047 */
/*主题:合并行 */
/*作者:二等草 */
/******************************************************************************/set nocount on--数据--------------------------------------------------------------------------
create table [ta] ([Tno] varchar(3),[ColA] varchar(1))
insert into [ta] select '001','A'
insert into [ta] select '001','B'
insert into [ta] select '001','C'
insert into [ta] select '001','D'
insert into [ta] select '001','E'
insert into [ta] select '002','A'
insert into [ta] select '002','C'
insert into [ta] select '002','D'
insert into [ta] select '002','E'
insert into [ta] select '002','G'
insert into [ta] select '003','A'
insert into [ta] select '003','C'
insert into [ta] select '004','B'
insert into [ta] select '004','F'
insert into [ta] select '004','I'
go--代码--------------------------------------------------------------------------
create function gets(@id varchar(10))
returns varchar(20)
as
begin
declare @s varchar(20)
select @s = isnull(@s,'')+cola from ta where tno=@id
return @s
end
go
select tno,dbo.gets(tno) from ta group by tno order by tno
go/*结果--------------------------------------------------------------------------
tno
---- --------------------
001 ABCDE
002 ACDEG
003 AC
004 BFI--清除------------------------------------------------------------------------*/
drop function gets
go
drop table ta