hibernate-issues

[Hibernate-issues] [Hibernate-JIRA] Created: (HHH-1837) discussion: implicit joins are always INNER

[Bill S. (JIRA) <no...@at...>]

discussion: implicit joins are always INNER
-------------------------------------------

         Key: HHH-1837
         URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-1837
     Project: Hibernate3
        Type: Improvement

    Reporter: Bill Schneider


It would be helpful to explain the consequences in the docs re. implicit joins always resulting in INNER joins.  
This causes semantics of HQL expressions to be quite different from similar-looking JSTL expressions.  

in particular consider (copied from comment on HHH-989) this HQL expression
"cat.mate.name= ? OR cat.name=?"

if cat.mate is null, this will not return any results, **even if**  the right hand cat.name=? expression matches.
A similar condition in JSTL (<c:if test="${cat.mate.name = ... || cat.name = ...}">) would behave differently.
The HQL behavior may be correct, but sure could be confusing at first.


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[Hibernate-issues] [Hibernate-JIRA] Closed: (HHH-1837) discussion: implicit joins are always INNER

[Max R. A. (JIRA) <no...@at...>]

     [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-1837?page=all ]
     
Max Rydahl Andersen closed HHH-1837:
------------------------------------

    Resolution: Rejected

HQL mimics SQL's ternary logic. 

JSTL and most other imperative languages only have binary logic.

Two very different things.

> discussion: implicit joins are always INNER
> -------------------------------------------
>
>          Key: HHH-1837
>          URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-1837
>      Project: Hibernate3
>         Type: Improvement

>     Reporter: Bill Schneider

>
>
> It would be helpful to explain the consequences in the docs re. implicit joins always resulting in INNER joins.  
> This causes semantics of HQL expressions to be quite different from similar-looking JSTL expressions.  
> in particular consider (copied from comment on HHH-989) this HQL expression
> "cat.mate.name= ? OR cat.name=?"
> if cat.mate is null, this will not return any results, **even if**  the right hand cat.name=? expression matches.
> A similar condition in JSTL (<c:if test="${cat.mate.name = ... || cat.name = ...}">) would behave differently.
> The HQL behavior may be correct, but sure could be confusing at first.

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[Hibernate-issues] [Hibernate-JIRA] Commented: (HHH-1837) discussion: implicit joins are always INNER

[Bill S. (JIRA) <no...@at...>]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-1837?page=comments#action_23338 ] 

Bill Schneider commented on HHH-1837:
-------------------------------------

This is really a request for documentation.  I agree the HQL behavior is correct. 

The only issue is that, because the implicit-join syntax looks deceptively similar to something you could have in JSTL-EL, the SQL inner-join behavior is not immediately obvious to someone looking at this as a Java developer.  

So I think it would be helpful to just include a blurb to the effect of the above in the section in the hibernate reference on HQL implicit joins.  

> discussion: implicit joins are always INNER
> -------------------------------------------
>
>          Key: HHH-1837
>          URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-1837
>      Project: Hibernate3
>         Type: Improvement

>     Reporter: Bill Schneider

>
>
> It would be helpful to explain the consequences in the docs re. implicit joins always resulting in INNER joins.  
> This causes semantics of HQL expressions to be quite different from similar-looking JSTL expressions.  
> in particular consider (copied from comment on HHH-989) this HQL expression
> "cat.mate.name= ? OR cat.name=?"
> if cat.mate is null, this will not return any results, **even if**  the right hand cat.name=? expression matches.
> A similar condition in JSTL (<c:if test="${cat.mate.name = ... || cat.name = ...}">) would behave differently.
> The HQL behavior may be correct, but sure could be confusing at first.

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[Hibernate-issues] [Hibernate-JIRA] Commented: (HHH-1837) discussion: implicit joins are always INNER

[Steve E. (JIRA) <no...@at...>]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-1837?page=comments#action_23341 ] 

Steve Ebersole commented on HHH-1837:
-------------------------------------

Not to mention it is already discussed in the doco:
http://www.hibernate.org/hib_docs/v3/reference/en/html/queryhql.html#queryhql-joins-forms


> discussion: implicit joins are always INNER
> -------------------------------------------
>
>          Key: HHH-1837
>          URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-1837
>      Project: Hibernate3
>         Type: Improvement

>     Reporter: Bill Schneider

>
>
> It would be helpful to explain the consequences in the docs re. implicit joins always resulting in INNER joins.  
> This causes semantics of HQL expressions to be quite different from similar-looking JSTL expressions.  
> in particular consider (copied from comment on HHH-989) this HQL expression
> "cat.mate.name= ? OR cat.name=?"
> if cat.mate is null, this will not return any results, **even if**  the right hand cat.name=? expression matches.
> A similar condition in JSTL (<c:if test="${cat.mate.name = ... || cat.name = ...}">) would behave differently.
> The HQL behavior may be correct, but sure could be confusing at first.

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