提出了递归CTE解决方案，但没有提供代码。下面的代码是递归CTE的示例。

请注意，虽然结果与问题相符，但数据与给定的描述并不完全相符，因为我假设您确实希望对行组（而不是表中的所有行）执行此操作。将其更改为与表中的所有行相匹配是读者的练习。

;WITH basetable AS (
    SELECT
        id,
        CAST(name AS VARCHAR(MAX)) name,
        ROW_NUMBER() OVER (Partition BY id ORDER BY seq) rw,
        COUNT(*) OVER (Partition BY id) recs
    FROM (VALUES
        (1, 'Johnny', 1),
        (1, 'M', 2),
        (2, 'Bill', 1),
        (2, 'S.', 4),
        (2, 'Preston', 5),
        (2, 'Esq.', 6),
        (3, 'Ted', 1),
        (3, 'Theodore', 2),
        (3, 'Logan', 3),
        (4, 'Peter', 1),
        (4, 'Paul', 2),
        (4, 'Mary', 3)
    ) g (id, name, seq)
),
rCTE AS (
    SELECT recs, id, name, rw
    FROM basetable
    WHERE rw = 1

    UNION ALL

    SELECT b.recs, r.ID, r.name +', '+ b.name name, r.rw + 1
    FROM basetable b
    INNER JOIN rCTE r ON b.id = r.id AND b.rw = r.rw + 1
)
SELECT name
FROM rCTE
WHERE recs = rw AND ID=4
OPTION (MAXRECURSION 101)

在Chris Shaffer的回答之上：

如果您的数据可能会重复，例如

Tom
Ali
John
Ali
Tom
Mike

而不是汤姆、阿里、约翰、阿里、汤姆、迈克

您可以使用DISTINCT避免重复，并让Tom、Ali、John、Mike：

DECLARE @Names VARCHAR(8000)
SELECT DISTINCT @Names = COALESCE(@Names + ',', '') + Name
FROM People
WHERE Name IS NOT NULL
SELECT @Names

在PostgreSQL中-array_agg

SELECT array_to_string(array_agg(DISTINCT rolname), ',') FROM pg_catalog.pg_roles;

或STRING_AGG

SELECT STRING_AGG(rolname::text,',') FROM pg_catalog.pg_roles;

此答案可能会返回意外的结果。要获得一致的结果，请使用其他答案中详细说明的For XML PATH方法之一。

使用COALENCE：

DECLARE @Names VARCHAR(8000) 
SELECT @Names = COALESCE(@Names + ', ', '') + Name 
FROM People

只是一些解释（因为这个答案似乎得到了相对规律的观点）：

联合实际上只是一种有助于实现两件事的欺骗：

1） 无需使用空字符串值初始化@Names。

2） 无需在末端去除额外的分隔符。

如果一行具有NULL Name值（如果存在NULL，NULL将使该行之后的@Names为NULL，而下一行将再次以空字符串开始），则上述解决方案将给出错误的结果。使用以下两种解决方案之一即可轻松解决：

DECLARE @Names VARCHAR(8000) 
SELECT @Names = COALESCE(@Names + ', ', '') + Name
FROM People
WHERE Name IS NOT NULL

or:

DECLARE @Names VARCHAR(8000) 
SELECT @Names = COALESCE(@Names + ', ', '') + 
    ISNULL(Name, 'N/A')
FROM People

取决于您想要的行为（第一个选项只是过滤掉NULL，第二个选项用标记消息将它们保留在列表中[用适合您的内容替换“N/a”]）。

使用递归查询，您可以执行以下操作：

-- Create example table
CREATE TABLE tmptable (NAME VARCHAR(30)) ;

-- Insert example data
INSERT INTO tmptable VALUES('PETER');
INSERT INTO tmptable VALUES('PAUL');
INSERT INTO tmptable VALUES('MARY');

-- Recurse query
with tblwithrank as (
select * , row_number() over(order by name) rang , count(*) over() NbRow
from tmptable
),
tmpRecursive as (
select *, cast(name as varchar(2000)) as AllName from tblwithrank  where rang=1
union all
select f0.*,  cast(f0.name + ',' + f1.AllName as varchar(2000)) as AllName 
from tblwithrank f0 inner join tmpRecursive f1 on f0.rang=f1.rang +1 
)
select AllName from tmpRecursive
where rang=NbRow

以下是实现这一目标的完整解决方案：

-- Table Creation
CREATE TABLE Tbl
( CustomerCode    VARCHAR(50)
, CustomerName    VARCHAR(50)
, Type VARCHAR(50)
,Items    VARCHAR(50)
)

insert into Tbl
SELECT 'C0001','Thomas','BREAKFAST','Milk'
union SELECT 'C0001','Thomas','BREAKFAST','Bread'
union SELECT 'C0001','Thomas','BREAKFAST','Egg'
union SELECT 'C0001','Thomas','LUNCH','Rice'
union SELECT 'C0001','Thomas','LUNCH','Fish Curry'
union SELECT 'C0001','Thomas','LUNCH','Lessy'
union SELECT 'C0002','JOSEPH','BREAKFAST','Bread'
union SELECT 'C0002','JOSEPH','BREAKFAST','Jam'
union SELECT 'C0002','JOSEPH','BREAKFAST','Tea'
union SELECT 'C0002','JOSEPH','Supper','Tea'
union SELECT 'C0002','JOSEPH','Brunch','Roti'

-- function creation
GO
CREATE  FUNCTION [dbo].[fn_GetItemsByType]
(   
    @CustomerCode VARCHAR(50)
    ,@Type VARCHAR(50)
)
RETURNS @ItemType TABLE  ( Items VARCHAR(5000) )
AS
BEGIN

        INSERT INTO @ItemType(Items)
    SELECT  STUFF((SELECT distinct ',' + [Items]
         FROM Tbl 
         WHERE CustomerCode = @CustomerCode
            AND Type=@Type
            FOR XML PATH(''))
        ,1,1,'') as  Items



    RETURN 
END

GO

-- fianl Query
DECLARE @cols AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX)

select @cols = STUFF((SELECT distinct ',' + QUOTENAME(Type) 
                    from Tbl
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = 'SELECT CustomerCode,CustomerName,' + @cols + '
             from 
             (
                select  
                    distinct CustomerCode
                    ,CustomerName
                    ,Type
                    ,F.Items
                    FROM Tbl T
                    CROSS APPLY [fn_GetItemsByType] (T.CustomerCode,T.Type) F
            ) x
            pivot 
            (
                max(Items)
                for Type in (' + @cols + ')
            ) p '

execute(@query)