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Re: [eclipselink-users] Join Table with additional columns: One SQL Select to fetch data?
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You can use join fetching or batch reading for this, either at the query
level, or the mapping level.
For mapping level, you can use the EclipseLink @JoinFetch annotation or xml
to always join the relationship from Courses to Course. You could also use
a DescriptorCustomizer to set enable batch reading on the OneToOneMapping
for course.
Joe Mc. wrote:
>
> Hi,
>
> I am playing with additional columns in join tables.
> The following example:
> Customer visits some Courses
> This n-m-Relation contains additional attributes in the n-m-table (join
> table), for example: note, year etc.
>
> One solution is to use @OneToMany and @ManyToOne with a concret join table
> in Java, insteed of @ManyToMany.
> In this Association class, is it possible to hold the additional columns
> This solution is fine and worked.
>
> In @ManyToMany is it possible to tell EclipseLink, that he use only ONE
> Select statement, to get all the data from the different tables (with
> outer joins etc.).
> Is it possible to do this now with the OneToMany and ManyToOne?
>
> At the moment I get a join of Customer and Courses. And EclipseLink fires
> for every Course, the customer holds, an additional SQL SELECT statement
> to get the data :-(
>
> I general: I want the same SQL SELECT statement as in the ManyToMany case.
> Is it possible?
>
>
> Thanks for any advice!
>
> Regards
>
> M.Joe
>
-----
http://wiki.eclipse.org/User:James.sutherland.oracle.com James Sutherland
http://www.eclipse.org/eclipselink/
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