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From "Michael Gentry" <blackn...@gmail.com>
Subject Re: Get the number of FKs
Date Thu, 06 Mar 2008 20:27:22 GMT
If it is mandatory, it sounds like these records were created outside
of Cayenne (they are legacy, testing, etc records)?  If that is the
case, the easiest thing to do is to just issue an SQL command directly
to the database (using whatever normal SQL command you use).
Something like:

delete from employee where departmentFK is null;

If it is something that is happening regularly, though, and you want
to be able to nuke them from within your Cayenne application, you can
issue raw SQL to do the trick, too:

DataContext dataContext = DataContext.createDataContext();
SQLTemplate sqlQuery = new SQLTemplate(Customer.class, "delete from
employee where departmentFK is null");
dataContext.performNonSelectingQuery(sqlQuery);

With this code, though, be careful that you don't have any of those
dangling employees in memory, as this totally bypasses the Cayenne
object graph.

/dev/mrg


On Thu, Mar 6, 2008 at 3:19 PM, Scott Anderson <sanderson@airvana.com> wrote:
> Employee.Department is mandatory; I want to search for and delete rogue
>  departments.
>
>
>
>  -----Original Message-----
>  From: Michael Gentry [mailto:blacknext@gmail.com]
>  Sent: Thursday, March 06, 2008 2:08 PM
>  To: user@cayenne.apache.org
>  Subject: Re: Get the number of FKs
>
>  It seems you mainly want a list of employees who are not in a
>  department, so doing a fetch on Employee where "department = null"
>  might work (I'm not positive I've ever tried this, but it seems logical
>  to me).
>
>  /dev/mrg
>
>  On Thu, Mar 6, 2008 at 1:58 PM, Scott Anderson <sanderson@airvana.com>
>  wrote:
>  > I've got a one-to-many relationship (employees belong to a
>  > department),  and I'd like to search for departments that have no
>  employees.
>  >  Currently, I have something like:
>  >
>  >  foreach(dept : departments) {
>  >     if(dept.getEmployees().size() == 0)
>  >         context.deleteObject(dept);
>  >  }
>  >
>  >  When I do this, it has the effect of telling Cayenne to fetch data
>  > rows  for every employee in the database; this will not scale well. Is
>
>  > there  any way I can get the size of the array without doing a custom
>  > SELECT  query?
>  >
>

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