[hibernate-dev] How to deal with a constant in CriteriaQuery

[Steve Ebersole]

JPA is technically under the old JCP still AFAIK.  So for now the process
would be the same it has always been.

I just do not see how this would ever get agreed upon for a standardized
contract - it is so very dependent upon how the provider models the query
(SQM e.g.) versus the specific mechanism they use to render it (SQL AST).


On Tue, Apr 24, 2018 at 9:29 AM Steve Ebersole <steve at hibernate.org> wrote:

> On Tue, Apr 24, 2018 at 8:45 AM Gail Badner <gbadner at redhat.com> wrote:
>
>> Yes, that should work with CriteriaQuery as well. It's a reasonable
>> workaround.
>>
>> If JPA doesn't support this now, is it something that should be supported
>> in the future?
>
>
> The problem with defining support for this in the spec is that it is
> relying on Hibernate's "SQL function registry" and its `SQLFunction`
> contract.  I seriously doubt we'd get all the EG members to agree to some
> standardization of anything like a `SQLFunction` contract.
>
> I think proposing to add additional functions to the spec as "built-in" is
> probably more likely.  I can especially see EXTRACT being likely.  Maybe
> DATEDIFF.  Oracle for sure does not support DATEDIFF, but it does support
> the EXTRACT-from-INTERVAL approach.   Anyone know offhand other databases
> which to not define DATEIDFF?
>
> I personally think having DATEDIFF defined as "built-in" is the best
> option as the provider can always map that to EXTRACT-from-INTERVAL for
> Oracle, etal - its much harder to do that by mapping EXTRACT-from-INTERVAL
> to DATEDIFF.
>