# Apply formula to referenced column name

**URL:** <https://discourse.hibernate.org/t/apply-formula-to-referenced-column-name/8326>\
**Category:** Hibernate ORM\
**Created:** [September 30, 2023, 10:28am UTC](https://discourse.hibernate.org/t/apply-formula-to-referenced-column-name/8326 "2023-09-30T10:28:00Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![niels](https://avatars.discourse-cdn.com/v4/letter/n/ebca7d/32.png) [@niels](https://discourse.hibernate.org/u/niels)\
**Post date:** [September 30, 2023, 10:28am UTC](https://discourse.hibernate.org/t/apply-formula-to-referenced-column-name/8326/1 "2023-09-30T10:28:00Z")

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Hi there,

I am mapping a (legacy) DB view to JPA/Hibernate entities. The view contains, among other things, the following join:

```auto
FROM a
JOIN b
  on trim(a.b_foo) = trim(b.foo)

```

I want to create a `@ManyToOne` relation from `A` entity to `B`.  
I know I can use `@JoinFormula` to trim the column of the owning (`A`) entity, but I was unable to find a way to apply a trim to the other part of the condition (as `referencedColumnName` only allows exact column names).  
It’s pretty straightforward in JPQL/QueryDSL/etc., but I want to do it in my relation so I don’t have to define this join in multiple queries.

Is there a way to do this without changing my DB schema (I don’t want to create a view of table `b` that trims the value nor do I want to add computed/virtual columns)?  
I am using Hibernate 6.

Thanks in advance

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<div class="post-metadata">

**Author:** ![beikov](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/beikov/32/258_2.png) [@beikov](https://discourse.hibernate.org/u/beikov)\
**Post date:** [October 2, 2023, 8:14am UTC](https://discourse.hibernate.org/t/apply-formula-to-referenced-column-name/8326/2 "2023-10-02T08:14:35Z")

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That’s not possible and IMO you also shouldn’t do this. This seems to be an ad-hoc association/relation which shouldn’t be part of your model. If it really is a proper relation of your model, you should consider adding the virtual column or trim the original column in the first place and create a FK constraint as well as an index.

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<div class="post-metadata">

**Author:** ![niels](https://avatars.discourse-cdn.com/v4/letter/n/ebca7d/32.png) [@niels](https://discourse.hibernate.org/u/niels)\
**Post date:** [October 2, 2023, 8:17am UTC](https://discourse.hibernate.org/t/apply-formula-to-referenced-column-name/8326/3 "2023-10-02T08:17:54Z")

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I agree that I “shouldn’t do this”, but I wanted to explore other options before considering to touch the legacy DB (schema) I’m working with. Thanks for your answer!