A fourth option (someway similar to the second one) is to use the Native
SQL Query feature of Hibernate. Instead of calling
session.createQuery(hql) you can call session.createSQLQuery(sql). It
works, using aliases. However, I tested it only on MySql and HSQLDB.
WDYT? Is this a convenient solution. I would have to switch many of the
hql queries from the Statistics Application to sql queries.
Marius
> Right.. but the error persists with the correction made. Not at the same
> level though.
>
> WARN util.JDBCExceptionReporter - SQL Error: 1054, SQLState: 42S22
> ERROR util.JDBCExceptionReporter - Unknown column 'pageViewsCount' in
> 'order clause'
>
> The problem is with Hibernate. There is a bug ("missing feature", for
> them) in the translation from HQL to SQL. The aliases from the Select
> clause are not resolved correctly in other clauses, including Order By. In
> this case they "recommend" us to duplicate the expressions from the Select
> clause, hoping that the RDBMS will take care of the optimization.
>
> See for yourself:
>
> http://opensource.atlassian.com/projects/hibernate/browse/HHH-892
> http://opensource.atlassian.com/projects/hibernate/browse/HHH-1902
> http://opensource.atlassian.com/projects/hibernate/browse/HHH-2390
> http://forum.hibernate.org/viewtopic.php?t=966075&postdays=0&postorder=asc&start=0
>
> So, using aliases breaks Hibernate and using expressions in the Order By
> clause is not supported by MySql 4.1.20. I don't see any clean solution
> for this. Some options are:
>
> * drop the Order By clause and sort on the Java side - No way, I don't
> think this is feasible.
> * skip Hibernate layer and use JDBC directly - Doable, the SQL query being
> not too complicated, but with cross DB issues.
> * tweak the HQL query - How?
>
> Any other options Sergiu?
>
> Marius
>
>> Marius Dumitru Florea wrote:
>>> Hi Jeremie,
>>>
>>> The sql query you suggested is cleaner and at least as efficient as the
>>> current one. It was my first option but unfortunately it's not
>>> supported
>>> by the newer versions of mysql. I've no idea why..
>>>
>>> mysql> select xws_name, sum(xws_page_views) as pageviewcount from
>>> xwikistatsdoc where xws_action='view' and xws_name like '%.%' group by
>>> xws_name order by pageviewscount desc;
>>> ERROR 1054 (42S22): Unknown column 'pageviewscount' in 'order clause'
>>>
>>
>> Note that there's a typo: pageviewcount <> pageview-S-count
>>
>>> Anyway, hibernate should be responsible for the correct translation
>>> from
>>> hql to a specific sql dialect. A solution would be to use the (idea
>>> from
>>> the) above sql but configure the dialect to MySQL5Dialect (in my case).
>>> I
>>> have to test this. I'll give you feedback soon.
>>>
>>> Best Regards,
>>> Marius.
>>>
>>
>> --
>> Sergiu Dumitriu
>> http://purl.org/net/sergiu/
>>
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