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From Oystein Grovlen - Sun Norway <Oystein.Grov...@Sun.COM>
Subject Re: Functions in GROUP BY expressions? (related to DERBY-883)
Date Tue, 14 Nov 2006 13:18:50 GMT
Yip Ng wrote:

> For SIN, COS, TAN functions,  they are also considered deterministics.  
> However, they do not work currently in Derby with group by expression as 
> they are mapped to  JavaToSQLValueNode and such nodes always return 
> false in isEquivalent() method, so I think this is an implementation 
> restriction for those built-in functions.

Just some late follow-up here.  As far as I can tell, it is not strictly 
correct to say that non-deterministic functions does not work with group 
by expressions.  What does not work is to use a non-deterministic 
function in the select list of a statement when grouping on the same 
function.  However, the following query works:

	select avg(i) from t group by sin(i)

I assume that it is the check for equivalence between the select list 
and the group by list that requires deterministic functions.  (This may 
have been clear to others when this was discussed, but at least not to me.)

-- 
Øystein

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