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From Rick Hillegas <rick.hille...@oracle.com>
Subject Re: Derby Key Words
Date Thu, 06 Sep 2012 18:16:09 GMT
Hi David,

Some comments inline...

...
> re your comment of String constants in an array. I found the same 
> thing in the interface.
>
> It has just occured to me that, as we use a database, maybe a 
> resultSet may be the thing to return , I've come full circle to 
> understanding your original idea of a 'Table Function'. But I would 
> still think that a function in DatabaseMetaData would be good.
>
> Along these lines... it should take a String argument that is the word 
> being tested, and return true [word is in list] or false [word is not 
> in the list]. I propose to call the method prototype to be something 
> like getAllDerbyKeyWords(String wordToTest) . Hopefully as it has the 
> word 'Derby' in it the SQL people are unlikely to ever use is in the 
> standard! Although maybe there would be an argument to propose a new 
> method of getAllKeywords() to the standard, that each driver vendor 
> could implement and would have the same / similar functionality - 
> delusions of grandeur ;)
The presence of Derby in the function name sounds good to me. I agree 
that that should prevent the JDBC spec from encroaching on this 
function. I'm afraid I don't understand the usefulness of the String 
argument. Having a no-arg function which returns all of the words sounds 
good enough to me. The restriction to a single string can be 
accomplished by this query against the resulting table function:

select keyword from table( getAllDerbyKeyWords() ) t where t.keyword = 
'wordToTest'

>
> But how to turn that String Array into a Table is fairly simple (I'd 
> declare a temp table), and then make a select on it to get a 
> resultSet. However is there a way to skip the table step and jump 
> straight to a result set (its a bit of a leading question, and I 
> haven't searched for an answer anywhere yet, so unless you know off 
> the top of your head no need to answer straight away).
The table function can just be an extension of 
org.apache.derby.vti.StringColumnVTI. All you have to implement are 3 
methods: next(), close(), and getRawColumn().

Hope this helps,
-Rick
>
> David
>


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