一对多的SQL视图咋搞呢?

Question

A表(客户表)       ID    ClientName  
                  1      CAA
                  2      CBB
                  3      CCCB表(客户联系人)   ClientID    ContactName  
                  1             AC1
                  1             AC2
                  1             AC3
                  2             BC1
                  2             BC2
                  3             CC1问...怎么得到以下查询结果(客户联系人逗号隔开)ClientName     Contacts
CAA            AC1,AC2,AC3
CBB            BC1,BC2
CCC            CC1

Answer 1

自己看合并列值 
原著：邹建 
改编：爱新觉罗.毓华(十八年风雨,守得冰山雪莲花开)  2007-12-16  广东深圳 表结构，数据如下： 
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(在sql server 2000中只能用函数解决。) 
--1. 创建处理函数 
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 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, value = dbo.f_str(id) FROM tb GROUP BY id drop table tb 
drop function dbo.f_str /* 
id          value      
----------- ----------- 
1          aa,bb 
2          aaa,bbb,ccc 
（所影响的行数为 2 行） 
*/ --2、另外一种函数. 
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 --创建一个合并的函数 
create function f_hb(@id int) 
returns varchar(8000) 
as 
begin 
  declare @str varchar(8000) 
  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 --调用自定义函数得到结果： 
select distinct id ,dbo.f_hb(id) as value from tb drop table tb 
drop function dbo.f_hb /* 
id          value      
----------- ----------- 
1          aa,bb 
2          aaa,bbb,ccc 
（所影响的行数为 2 行） 
*/ 2. 新的解决方法(在sql server 2005中用OUTER APPLY等解决。) 
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') 
go 
-- 查询处理 
SELECT * FROM(SELECT DISTINCT id FROM tb)A OUTER APPLY( 
        SELECT [values]= STUFF(REPLACE(REPLACE( 
            ( 
                SELECT value FROM tb N 
                WHERE id = A.id 
                FOR XML AUTO 
            ), ' <N value="', ','), '"/>', ''), 1, 1, '') 
)N 
drop table tb /* 
id          values 
----------- ----------- 
1          aa,bb 
2          aaa,bbb,ccc (2 行受影响) 
*/ --SQL2005中的方法2 
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 select id, [values]=stuff((select ','+[value] from tb t where id=tb.id for xml path('')), 1, 1, '') 
from tb 
group by id /* 
id          values 
----------- -------------------- 
1          aa,bb 
2          aaa,bbb,ccc (2 row(s) affected) */ drop table tb 

Answer 2

--> 测试数据：[ta]
if object_id('[ta]') is not null drop table [ta]
go
create table [ta]([ID] int,[ClientName] varchar(3))
insert [ta]
select 1,'CAA' union all
select 2,'CBB' union all
select 3,'CCC'--> 测试数据：[tb]
if object_id('[tb]') is not null drop table [tb]
go
create table [tb]([ClientID] int,[ContactName] varchar(3))
insert [tb]
select 1,'AC1' union all
select 1,'AC2' union all
select 1,'AC3' union all
select 2,'BC1' union all
select 2,'BC2' union all
select 3,'CC1'
--------------------------------查询开始------------------------------select a.[ClientName],b. [ContactName] from [ta] a
join
(
select [ClientID],
[ContactName]=stuff((select ','+[ContactName] from [tb] where [ClientID]=a.[ClientID] for xml path('')),1,1,'') 
from [tb] a
group by [ClientID]
)b 
on a.[id]=b.[ClientID]
/*
ClientName ContactName
---------- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
CAA        AC1,AC2,AC3
CBB        BC1,BC2
CCC        CC1(3 行受影响)*/