Joins with Toplink : Strange Problem!

Question

Hi!
I'm trying get the data from EMP table where the column mgr (ValueHolderInterface instance in Toplink POJO) is a self referential key to the empno.
Now I want to execute a query like this :
SELECT t0.EMPNO, t0.ENAME, t0.JOB , t0.MGR FROM EMP t0, EMP t1 WHERE (t1.EMPNO = t0.MGR);
And I used ReportQuery to get this ;
see the following code
Session session = getSessionFactory().acquireSession();
ExpressionBuilder builder = new ExpressionBuilder();
Expression expression = builder.get("mgr").get("empno").equal(builder.get("empno") );;
ReportQuery query = new ReportQuery(Emp.class,builder);
query.addAttribute("empno");
query.addAttribute("ename");
query.addAttribute("job");
query.addAttribute("mgr",builder.get("mgr").get("empno"));
query.addAttribute("mgr",expression);
query.dontMaintainCache();
List<ReportQueryResult> results = (List<ReportQueryResult> )
session.executeQuery(query);
And the Toplink Generated SQL is :
SELECT t0.EMPNO, t0.ENAME, t0.JOB, t1.EMPNO FROM EMP t0, EMP t1 WHERE (t1.EMPNO = t0.MGR)
which is almost similar.
But I'm getting an exception as below:
Exception [TOPLINK-4002] (Oracle TopLink - 10g Release 3 (10.1.3.1.0) (Build 061004)): oracle.toplink.exceptions.DatabaseException
Internal Exception: java.sql.SQLException: ORA-00904: "T0"."MGR": invalid identifier
Error Code: 904
Further ,
I tried to get the data from multile tables as below:
The intended SQL :
SELECT E.EMPNO,E.ENAME,E.JOB,E.MGR,E.SAL,E.DEPTNO,D.DNAME,D.LOC FROM EMP E, DEPT D WHERE E.DEPTNO=D.DEPTNO;
And for this I wrote the code as below :
ExpressionBuilder builder = new ExpressionBuilder();
Expression expression = builder.get("dept").get("deptno").equal( builder.get("dept").get("deptno"));;
ReportQuery query = new ReportQuery(Emp.class,builder);
query.addAttribute("empno");
query.addAttribute("ename");
query.addAttribute("job");
//query.addAttribute("mgr",builder.get("mgr").get("empno"));
// query.addAttribute("mgr");
query.addAttribute("ename");
query.addAttribute("sal");
query.addAttribute("deptno",builder.get("dept").get("deptno"));
//query.addAttribute("dept",expression);
query.addAttribute("dname",builder.get("dept").get("dname"));
query.addAttribute("loc",builder.get("dept").get("loc"));
query.dontMaintainCache();
//query.addAttribute("mgr",expression);
List<ReportQueryResult> results = (List<ReportQueryResult> ) session.executeQuery(query);
And the Query Generated by the Toplink is :
SELECT t0.EMPNO, t0.ENAME, t0.JOB, t0.ENAME, t0.SAL, t1.DEPTNO, t1.DNAME, t1.LOC FROM EMP t0, DEPT t1 WHERE (t1.DEPTNO = t0.DEPTNO);
which is perfect .
But the Toplink error message is :Internal Exception: java.sql.SQLException: ORA-00904: "T0"."SAL": invalid identifier
Error Code: 904
And I tried to do this using ReadAll Query as below :
The code I wrote is :
ExpressionBuilder builder =new ExpressionBuilder();
// Expression expression = builder.get("");
ReadAllQuery query = new ReadAllQuery(Emp.class,builder);
query.addJoinedAttribute("dept");
query.dontMaintainCache();
List results = (List) session.executeQuery(query);
The Toplink Generated SQL is :
SELECT t1.EMPNO, t1.ENAME, t1.JOB, t1.HIREDATE, t1.EMPDET, t1.SAL, t1.COMM, t1.DEPTNO, t1.MGR, t0.DEPTNO, t0.DNAME, t0.LOC FROM DEPT t0, EMP t1 WHERE (t0.DEPTNO = t1.DEPTNO)
And the error is :
Internal Exception: java.sql.SQLException: ORA-00904: "T1"."MGR": invalid identifier
Error Code: 904
What mistake am I making ?
The generated SQL from the Toplink is working fine, I tested it.. but the Strange error message given are puzzling me..
Could anyone point me where I'm wrong ?
Thanks in advance,
Samba.

Answer 1

Looks like you were trying to use the attributes being returned to define the query's selection criteria.
To find self-reference manager's in our shipped Employee example I can use:
        ExpressionBuilder eb = new ExpressionBuilder();
        ReportQuery rq = new ReportQuery(Employee.class, eb);
        rq.addAttribute("id");
        rq.addAttribute("firstName");
        rq.addAttribute("lastName");
        rq.setSelectionCriteria(eb.get("manager").get("id").equal(eb.get("id")));
        List<ReportQueryResult> results = (List<ReportQueryResult> ) session.executeQuery(rq);
    }and the generated SQL is: (note: multi-table mapping sith SALARY in use)
SELECT t0.EMP_ID, t0.F_NAME, t0.L_NAME FROM SALARY t3, EMPLOYEE t2, SALARY t1, EMPLOYEE t0 WHERE (((t2.EMP_ID = t0.EMP_ID) AND (t1.EMP_ID = t0.EMP_ID)) AND ((t2.EMP_ID = t0.MANAGER_ID) AND (t3.EMP_ID = t2.EMP_ID)))If you also add a direct query-key for the manager's id ('managerId') we can avoid the self join:
        ExpressionBuilder eb = new ExpressionBuilder();
        ReportQuery rq = new ReportQuery(Employee.class, eb);
        rq.addAttribute("id");
        rq.addAttribute("firstName");
        rq.addAttribute("lastName");
        rq.setSelectionCriteria(eb.get("managerId").equal(eb.get("id")));
        List<ReportQueryResult> results = (List<ReportQueryResult> ) session.executeQuery(rq);And the SQL looks like:
SELECT t0.EMP_ID, t0.F_NAME, t0.L_NAME FROM EMPLOYEE t0, SALARY t1 WHERE ((t0.MANAGER_ID = t0.EMP_ID) AND (t1.EMP_ID = t0.EMP_ID))Cheers,
Doug