create table #workingtable (
    i int not null,
    vc varchar(50) not null,
    list varchar(8000),
    constraint pk_wt primary key (i,vc) )

insert into #workingtable (i,vc)
SELECT c.Class_ID AS Class_ID, ci.Instructor_Name AS Instructor_Name
FROM CLASS c
INNER JOIN Class_Instructor ci ON c.Class_ID = ci.Class_ID
ORDER BY c.Class_ID

declare
    @list varchar(8000),
    @lasti int

select
    @list = '',
    @lasti = -1

--here is the meat of the work
update
    #workingtable
set
    @list = list = case
                       when @lasti <> i then vc
                       else @list + ', ' + vc
                   end,
    @lasti = i

--return a sample from the final rowset
select top 10
    i,
    case
        when len(max(list)) > 50 then convert(varchar(50), left(max(list),47) + '...')
        else convert(varchar(50),max(list))
    end as Instructor_Name
from
    #workingtable
group by
    i
order by
    newid()
go

DROP TABLE #workingtable

SET NOCOUNT ON

CREATE TABLE CLASS
(
Class_ID INT NOT NULL,
Class_Name VARCHAR(50) NOT NULL
)

CREATE TABLE Class_Instructor
(
Class_Instructor_ID INT NOT NULL,
Class_ID INT NOT NULL,
Instructor_Name VARCHAR(50) NOT NULL
)

INSERT INTO CLASS VALUES(1, 'English')
INSERT INTO CLASS VALUES(2, 'Math')
INSERT INTO CLASS VALUES(3, 'Science')

INSERT INTO Class_Instructor VALUES(1, 1, 'Tom Jones')
INSERT INTO Class_Instructor VALUES(2, 1, 'Pete Moss')

SELECT c.Class_ID, ci.Instructor_Name
FROM CLASS c
INNER JOIN Class_Instructor ci ON c.Class_ID = ci.Class_ID

DROP TABLE Class
DROP TABLE Class_Instructor