Database Software

Hi all!
I have some problem with querying xml data.
Simplified description follows:

Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production - Linux

I have 3 rows:
a           x
1     <a>1</a>
2     <a>2</a>
3     <a>3</a>

and want to have
a           x                  x1
1     <a>1</a>     <a>1</a>
2     <a>2</a>     <a>1</a>
3     <a>3</a>     <a>1</a>
as a result.


This query

with d0 as (
*                   select 1 a, xmlelement("a", 1) x from dual*
*  union all select 2 a, xmlelement("a", 2) x from dual*
*  union all select 3 a, xmlelement("a", 3) x from dual*
*)*
select a, x, xmlconcat(x) keep (dense_rank first order by a) over (partition by 0) x1
*  from d0;*

throws
ORA-03113: ....

What am I doing wrong? Or is it a bug?

Is it possible to get result not using query like this:

with d0 as (
*                   select 1 a, xmlelement("a", 1) x from dual*
*  union all select 2 a, xmlelement("a", 2) x from dual*
*  union all select 3 a, xmlelement("a", 3) x from dual*
*)*
select a, x, (select x from d0 where a = 1) x1
*  from d0;*

Thank you!