Here is some code you can work with on this.

declare @TestTab table (ColA int, ColB Varchar(10));

insert into @TestTab

select 1, 'John' union all

select 1, 'Josh' union all

select 1, 'Bob' union all

select 2, 'Kathy' union all

select 2, 'Jill'

;

select * from @TestTab;

select

ColA,

stuff((select ', ' + ColB from @TestTab t2 where t2.ColA = t1.ColA for xml path('')),1,2,'')

from

@TestTab t1

group by

ColA;