SQL> with emp as ( select 123 empno, 'O''Brien' ename from dual )
  2  select
  3    xmlelement("blah",
  4      xmlforest(e.empno as "empid",
  5                e.ename as "name")
  6      )
  7  from emp e;

XMLELEMENT("BLAH",XMLFOREST(E.EMPNOAS"EMPID",E.ENAMEAS"NAME"))
------------------------------------------------------------------------------------------
<blah><empid>123</empid><name>O&apos;Brien</name></blah>

SQL>
SQL> set serverout on
SQL> declare
  2    x xmltype;
  3    new_x xmltype;
  4  begin
  5    with emp as ( select 123 empno, 'O''Brien' ename from dual )
  6    select
  7      xmlelement("blah",
  8        xmlforest(e.empno as "empid",
  9                  e.ename as "name")
 10        )
 11    into x
 12    from emp e;
 13
 14    dbms_output.put_line(x.getClobVal());
 15    new_x := xmltype(dbms_xmlgen.convert(x.getClobVal(), dbms_xmlgen.ENTITY_DECODE));
 16    dbms_output.put_line(new_x.getClobVal());
 17
 18  end;
 19  /
<blah><empid>123</empid><name>O&apos;Brien</name></blah>
<blah><empid>123</empid><name>O'Brien</name></blah>

PL/SQL procedure successfully completed.