declare @t table (AA int,BB varchar(1),CC varchar(1))
insert into @t
select 1,'a','A' union all
select 1,'a','B' union all
select 1,'b','A' union all
select 1,'b','C' union all
select 2,'a','C' union all
select 2,'a','B'
SELECT * FROM @t

SELECT AA,a=ISNULL(a,'-'),b=ISNULL(b,'-'),c=ISNULL(c,'-') FROM
(SELECT *,dd=bb FROM @t) a
PIVOT
(MAX(dd) FOR CC IN ([A],[B],[C])) b
ORDER BY AA
/*
AA    a    b    c
1    a    a    -
1    b    -    b
2    -    a    a
*/