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https://issues.apache.org/jira/browse/OPENJPA-273?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12510199
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Patrick Linskey commented on OPENJPA-273:
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Another potential approach: create some syntax for escaping a part of a query
to SQL, and then permit nested escapes back to JPQL (or at least JPQL
parameters and path expressions) from within the SQL bits. The query that I
mentioned above might look like so:
select :sql{stdev(:jpql{emp.salary})} from Employee emp
This has the advantage of permitting arbitrary SQL (excepting the escape
sequence, which is ':jpql{' here) to be used. So, we can do an EXTRACT function
like so:
select distinct :sql{EXTRACT(year FROM :jpql{emp.hireDate})} from Employee
emp
> Native functions in JPQL; functions available in more clauses
> -------------------------------------------------------------
>
> Key: OPENJPA-273
> URL: https://issues.apache.org/jira/browse/OPENJPA-273
> Project: OpenJPA
> Issue Type: New Feature
> Components: jdbc, kernel, query
> Affects Versions: 0.9.0, 0.9.6, 0.9.7
> Reporter: Patrick Linskey
> Attachments: OPENJPA-273.patch
>
>
> JPQL has rather limited support for functions, in two ways. First, only a
> limited number of commonly-available functions are available in the language,
> and second, functions can only be used in a limited number of places in the
> grammar. This can be, well, limiting.
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