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From Rainer Döbele <doeb...@esteam.de>
Subject AW: year "functionName" for Oracle
Date Sun, 10 Oct 2010 21:20:48 GMT
Dear Marcio,

I appreciate your concern and indeed we should consider this.
In Oracle using TO_CHAR(someDateColumn, 'YYYY') can be used to extract the year from a date
as a string but I must admit that one would probably expect the year function to return a
number.

We could wrap this and perform a number conversion, but IMO using EXTRACT(YEAR FROM someDateColumn)
would be a much better way of implementing this. However it has only been available since
Oracle 9i.

As far as your test proposal is concerned I don't think checking for the function name as
you suggested does make any sense.
How a particular SQL function is rendered to SQL is up to the driver and the implementation
may change any time or even be different for different versions of a particular engine.
Ideally you should write test that really extracts the year from a date stored in the database
and check the result. This requires a complex test environment with all databases running
and is probably not feasible - but the only way to know the truth.

So since I am sure, that there are not many people using Oracle 8 or an earlier version any
more, I will change the default implementation for the date extraction functions (day, month,
year) to the Oracle extract function mentioned above. I may add a switch for Oracle 8 compatibility.
Does anyone have concerns about this?

Regards,
Rainer


Marcio Mazza wrote:
> from: Marcio Mazza [mailto:marciomazza@gmail.com]
> to: empire-db-dev@incubator.apache.org
> re: year "functionName" for Oracle
> 
> I'm in doubt if the method
>   org.apache.empire.db.expr.column.DBFuncExpr.getFunctionName()
> 
> will work fine with Oracle, for some date related functions.
> 
> I think the method it is called just for generating XML.
> Maybe a *test* for such feature should be done for the Oracle driver.
> 
> I attach a sample test (for the year function) to make things clearer.
> Oracle has a "strange" name for the year function. Is that correct?

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