var 
mNo : String;
begin
//假定A是得到后查询结果
//使用下面的语句
with A do begin
  mNo='';  
  first;
  while not eof do
    begin
      mNo := mNo+ Trim(FieldByName('OrderNo').AsString); 
      next;
    end;
  end;
end; 

-- 示例数据 
DECLARE @t TABLE(id int, value varchar(10)) 
INSERT @t SELECT 1, 'aaa' 
UNION ALL SELECT 1, 'bbb' 
UNION ALL SELECT 1, '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 

DECLARE @t TABLE(id int, value varchar(10)) 
INSERT @t SELECT 1, 'aaa' 
UNION ALL SELECT 1, 'bbb' 
UNION ALL SELECT 1, 'ccc' 


DECLARE @s VARCHAR(8000)
SELECT @s=ISNULL(@s,'')+value FROM @t
SELECT @s

DECLARE @t TABLE(id int, value varchar(10)) 
INSERT @t SELECT 1, 'aaa' 
UNION ALL SELECT 1, 'bbb' 
UNION ALL SELECT 1, 'ccc' 


SELECT CAST((SELECT * FROM @t FOR XML RAW) AS XML).query('for $v in //row/@value return string($v)')

Create table Tab([Col1] int,[Col2] nvarchar(1))
Insert Tab
select 1,N'a' union all
select 1,N'b' union all 
select 1,N'c' union all 
select 2,N'd' union all 
select 2,N'e' union all 
select 3,N'f' 
Go 

create function F_Str(@Col1 int) 
returns nvarchar(100) 
as 
begin     
declare 
@S nvarchar(100)    
select @S=isnull(@S+',','')+Col2 from Tab where Col1=@Col1     
return @S 
end 
go 
Select distinct Col1,Col2=dbo.F_Str(Col1) from Tab 
go