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Editorial Team
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Asked: 2026-05-19T11:24:19+00:00

We are trying to build a One-to-many relation. Trying to understand how this works,

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We are trying to build a One-to-many relation. Trying to understand how this works, we stumbled across this example, which shows how to do it.

The example shows a reasonable ER diagram, but generally speaking in a One-to-many relation one doesn’t need an auxiliary table. We could insert a StudentId column into the Phone table and achieve the linking by joining the two tables through this identifier. In the example, by contrast, they need to join three tables instead.

We are wondering if such a behaviour is justified by some good practice which makes the management easy for Hibernate or if it’s just an error of the guy who wrote the article.

Any thoughts?

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1 Answer

  1. Editorial Team

    I’ve found an answer, and it seems it’s exactly a sort of workaround…
    http://en.wikibooks.org/wiki/Java_Persistence/OneToMany#Join_Table

    Normally it is best to define the ManyToOne back reference in Java, if you cannot or don’t want to do this, then you can use a intermediate join table to store the relationship. This is similar to a ManyToMany relationship, but if you add a unique constraint to the target foreign key you can enforce that it is OneToMany.

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