ORA-19208: parameter 1 of function XMLFOREST must be aliased

Question

I'm running the below query on 10gR2 against the sample HR schema and getting the ORA-19208 error. I've aliased everything I can see and am still getting the error. What am I missing?
Thanks,
Bob S.
select XMLRoot(
XMLElement("DEPARTMENT",
XMLForest(D.DEPARTMENT_ID as "D1",
D.DEPARTMENT_NAME as "D2",
D.MANAGER_ID as "D3",
D.LOCATION_ID as "D4") as "AAA",
XMLForest(
(select XMLAgg(
XMLElement("EMPLOYEE",
XMLForest(E.EMPLOYEE_ID as "E1",
E.FIRST_NAME as "E2",
E.LAST_NAME as "E3",
E.EMAIL as "E4",
E.PHONE_NUMBER as "E5",
E.HIRE_DATE as "E6",
E.JOB_ID as "E7",
E.SALARY as "E8",
E.COMMISSION_PCT as "E9",
E.MANAGER_ID as "E10",
E.DEPARTMENT_ID as "E11") as "BBB",
XMLForest(
(select XMLAgg(
XMLElement("JOB HISTORY",
XMLForest(JH.EMPLOYEE_ID as "JH1",
JH.START_DATE as "JH2",
JH.END_DATE as "JH3",
JH.JOB_ID as "JH4",
JH.DEPARTMENT_ID as "JH5") as "CCC" ))
from HR.JOB_HISTORY JH
left outer join HR.EMPLOYEES E on E.EMPLOYEE_ID = JH.EMPLOYEE_ID
left join HR.DEPARTMENTS D2 on D2.DEPARTMENT_ID = JH.DEPARTMENT_ID
left join HR.JOBS J2 on J2.JOB_ID = JH.JOB_ID)) as "EEE"))
from HR.EMPLOYEES E
join HR.JOBS J on J.JOB_ID = E.JOB_ID
where D.DEPARTMENT_ID = E.DEPARTMENT_ID
) as "DDD")
,VERSION '1.0', STANDALONE NO) as "XXX"
from HR.DEPARTMENTS D;

Answer 1

The two subqueries were not aliased, I've added aliases "MAX1" and "MAX2"...
select XMLRoot(
         XMLElement("DEPARTMENT",
                    XMLForest(D.DEPARTMENT_ID as "D1",
                              D.DEPARTMENT_NAME as "D2",
                              D.MANAGER_ID as "D3",
                              D.LOCATION_ID as "D4"
                              ) as "AAA",
                    XMLForest(
                               (select
                                  XMLAgg(
                                    XMLElement("EMPLOYEE",
                                               XMLForest(E.EMPLOYEE_ID as "E1",
                                                         E.FIRST_NAME as "E2",
                                                         E.LAST_NAME as "E3",
                                                         E.EMAIL as "E4",
                                                         E.PHONE_NUMBER as "E5",
                                                         E.HIRE_DATE as "E6",
                                                         E.JOB_ID as "E7",
                                                         E.SALARY as "E8",
                                                         E.COMMISSION_PCT as "E9",
                                                         E.MANAGER_ID as "E10",
                                                         E.DEPARTMENT_ID as "E11"
                                                         ) as "BBB",
                                               XMLForest(
                                                          (select
                                                              XMLAgg(
                                                                 XMLElement("JOB HISTORY",
                                                                            XMLForest(JH.EMPLOYEE_ID as "JH1",
                                                                                      JH.START_DATE as "JH2",
                                                                                      JH.END_DATE as "JH3",
                                                                                      JH.JOB_ID as "JH4",
                                                                                      JH.DEPARTMENT_ID as "JH5"
                                                                                      ) as "CCC"
                                                             from HR.JOB_HISTORY JH
                                                             left outer join HR.EMPLOYEES E on E.EMPLOYEE_ID = JH.EMPLOYEE_ID
                                                             left join HR.DEPARTMENTS D2 on D2.DEPARTMENT_ID = JH.DEPARTMENT_ID
                                                             left join HR.JOBS J2 on J2.JOB_ID = JH.JOB_ID
                                                           ) as "MAX1" -- This was one missing alias
                                                         ) as "EEE"
                                  from HR.EMPLOYEES E
                                  join HR.JOBS J on J.JOB_ID = E.JOB_ID
                                 where D.DEPARTMENT_ID = E.DEPARTMENT_ID
                                ) as "MAX2" -- This was another missing alias
                              ) as "DDD"
               VERSION '1.0',
               STANDALONE NO
               ) as "XXX"
  from HR.DEPARTMENTS D;Max
[My Italian Oracle blog|http://oracleitalia.wordpress.com/2010/01/17/supporto-di-xml-schema-in-oracle-xmldb/]