SQL Question - Marking multiple columns for given data

Question

Hello everybody,
I have an sql problem that I can't solve.
Any comments, examples or resources will be welcomed about situation. I believe 'net is full of examples like this but I really can't realize how to search this.
My data is something like this:
        ID      CTYPE
         1          1
         1          1
         1          2
         2          4
         3          3
         3          1
         4          5
         5          8
         6          9And desired output is:
ID TYPE1 TYPE2 TYPE3 TYPE4
  1     X     X           
  2                       X
  3     X           X      You may reproduce the case with:
drop table bilal_deneme purge;
create table bilal_deneme(id number, ctype number);
insert into bilal_deneme values(1,1);
insert into bilal_deneme values(1,1);
insert into bilal_deneme values(1,2);
insert into bilal_deneme values(2,4);
insert into bilal_deneme values(3,3);
insert into bilal_deneme values(3,1);
insert into bilal_deneme values(4,5);
insert into bilal_deneme values(5,8);
insert into bilal_deneme values(6,9);
select * from bilal_deneme;Thanks in advance.

Answer 1

This may give you a start
SQL> select id,max(decode(ctype,1,'X')) "1",
  2            max(decode(ctype,2,'X')) "2",
  3            max(decode(ctype,3,'X')) "3"
  4  from bilal_deneme purge
  5  group by id;
        ID 1 2 3
         1 X X
         6
         2
         4
         5
         3 X   X
6 rows selected.