set nocount on
create table #t(column1 varchar( 10 ), column2 varchar( 10 ), column3 varchar( 10 ))

insert #t values('a1', 'b1', 'c1' )
insert #t values('a1', 'b1', 'c2' )
insert #t values('a1', 'b2', 'c3' )


SELECT  1             AS tag, 
       NULL         AS parent,
column1	as [column1! 1 !name],
NULL as [column2! 2 !name],
NULL as [column3! 3 !name]
from (select distinct column1 from #t) AS a
union all
select  2 , 1 , a.column1, b.column2, NULL
from (select distinct column1 from #t) AS a, (select distinct column1, column2 from #t) AS b
where a.column1 = b.column1
union all
select  3 , 2 ,a.column1, a.column2, b.column3
from (select distinct column1, column2 from #t) AS a, (select distinct column1, column2, column3 from #t) AS b
where a.column1 = b.column1 and a.column2 = b.column2
order by [column1! 1 !name], [column2! 2 !name], [column3! 3 !name]
for xml explicit

drop table #t

set nocount on
create table #t(column1 varchar( 10 ), column2 varchar( 10 ), column3 varchar( 10 ))

insert #t values('a1', 'b1', 'c1' )
insert #t values('a1', 'b1', 'c2' )
insert #t values('a1', 'b2', 'c3' )

select distinct column1.column1 as name, 
column2.column2 as name, column3.column3 as name
from 
((#t column3 left outer join #t column2 on column2.column2=column3.column2 and column2.column1=column3.column1) 
left outer join #t column1 on column1.column1=column2.column1) 
for xml auto

drop table #t