So whenever I want to associate employees to a department I either create a new employee or move employee from some other department ? I am talking about the case when a "employee" object is currently without any associated department. When we want to assign it to a department the following query will not include the employee I am interested in - "select * from DEPARTMENT left outer join EMPLOYEE on DEPARTMENT.ID = EMPLOYEE.DEPARTMENTID " A right join on the other hand will leave out all the 'departmemt' objects without any employee.
Thanks -Umesh Tyagi -----Original Message----- From: Kevin Williams [mailto:[EMAIL PROTECTED] Sent: Monday, April 23, 2007 12:43 PM To: [email protected] Subject: Re: RDB DAS - How to create non containment association ? If you want departments and their related employees then you would typically use a left join rather than a full join. At least, this is the scenario I see used most often. Our test case: RelationshipTests.testRelationshipModification2() demonstrates this. Thanks, --Kevin To read a set of departments and related employees you would typically use a left outer join rather than a full join since you want On 4/21/07, Umesh Tyagi (utyagi) <[EMAIL PROTECTED]> wrote: > > How to create non containment association between two existing objects ? > For example, lets assume the following relationship is a non > containment association i.e. both objects can exist independently of > each other - > > ------------ ---------- > |DEPARTMENT| 1______________* |EMPLOYEE| > ------------ ---------- > > Playing with samples code I have noticed that in order to create > association between two object they need to be part of the same data > graph generated by a single query. So for the following line to work - > > department.getList("employees").add(employee) > > both 'department' and 'employee' dataobjects must be under same root > DataObject instance. To achieve this I tried to do a full outer join > between DEPARTMENT and EMPLOYEE but it is not supported by derby or > hsql. The equivalent union result is not typed to DEPARTMENT and > EMPLOYEE by DAS. The other option is to set the foreign key value > explicitly in the 'employee' object, but it is not desirable. Any > other ideas ? > > -Umesh Tyagi > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
