SQL & PL/SQL

Hello.

I have the following XML:

<Rowset>

  <Row>

    <Code>01</Code>

    <Details>123</Details>

  </Row>

  <Row>

    <Code>03</Code>

    <Details>1233</Details>

  </Row>

  <Row>

    <Code>07</Code>

    <Details>12333</Details>

  </Row>

</Rowset>

I nedd to extract data 1 in sql query in this format:

CodesList

--------------

01,02,03

I'm using th following code:

select RTRIM(XMLAGG(XMLELEMENT(E,t.process_xml || ',')).EXTRACT('Rowset/Row/Code/text()').GETStringVAL(),',') from table1 t

The XML is in clob "process_xml".

But got the error message: ora-19011 character string buffer too small oracle

Help, please.