Is it now legal to select multiple items using EJBQL? I haven't
looked at the 3.0 syntax much.
-dain
On Feb 22, 2007, at 4:54 PM, Craig L Russell wrote:
How about
select dept, oldtimers from Department dept LEFT JOIN
dept.employeeCollection oldtimers WHERE dept.deptno >= 100 AND
oldtimers.yearsOfService >= 15
That should give you only departments that satisfy the deptno
constraint and since you are not using outer join, only departments
that also have at least one employee satisfying the yearsOfService
constraint.
The results would have one element for each employee. Each result
row would contain the department and the employee. So you would
have the results:
[looks better in monospace font]
dept oldtimers
============= ==============
R&D Larry
R&D Curly
R&D Moe
Entertainment Fred
Entertainment Ginger
Craig
On Feb 22, 2007, at 12:21 PM, Tom Mutdosch wrote:
Hi there,
I have a question about JPA Queries containing relationships and a
WHERE filter. I basically want to have a JSF page containing a
datatable that shows a list of Departments - each Department row
shows relevant columns (department name, ID, etc) as well as a
nested list of that Department's Employees with 15 or more years
of service.
I was wondering if there was any way to create a JPA query that
would return me such a result using just a single query. From
what I have heard, I don't believe this is possible but thought
I'd ask here just to be sure. As far as I know, JPA will just
return me the Departments that match that query and each
Department will contain every Employee that belongs to it.
Background: I have a DEPARTMENT entity with a one-to-many
relationship to an EMPLOYEE entity. On my web page, I want to
display "departments with a department number >= 100 and
containing EMPLOYEES with more than 15 years of service".
Using SDOs I was able to write a query that would return a List of
results which I would then bind to my JSF datatable. This list
would contain Departments, and the Departments would have the
Employees that matched that criteria. To do something similar in
JPA, I think I now need to do n + 1 queries. That is, one query
to retrieve the departments that I want to display, and then for
each department another query to get the filtered list of its
Employees.
In summary, I basically want to do something like:
select d from Department d LEFT JOIN d.employeeCollection e WHERE
d.deptno >= 100 AND e.yearsOfService >= 15
But I think I need to do two separate queries. One to get the
departments:
select d from Department d WHERE d.deptno >= 100
Then for each Department returned in that result set, a separate
query to get the employees I'm after:
select e from Employee e where e.department.deptno = d.deptno and
e.yearsOfService >= 15
Does this sound like the right/only way to do this?
Thanks,
Tom
Craig Russell
Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
408 276-5638 mailto:[EMAIL PROTECTED]
P.S. A good JDO? O, Gasp!
