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From Craig L Russell <Craig.Russ...@Sun.COM>
Subject Re: Assertion A14.6.9-7
Date Mon, 07 Nov 2005 18:33:47 GMT
Hi Michael,

On Nov 7, 2005, at 7:43 AM, Michael Watzek wrote:

> Hi Craig,
>
> assertion A14.6.9-7 specifies:
>
> "A14.6.9-7 [If the returned value from a query specifying a result  
> is null, this indicates that the expression specified as the result  
> was null.] Note that the semantics of this result are different  
> from the returned value where no instances satisfied the filter."
>
> Is my understanding right that the assertion checks if the result  
> expression evaluates to null? Does it make sense to test 3 queries,  
> one unique query and two non-unique queries, e.g.:
>
The test data:

emp1.manager is emp2.
emp2.manager is null.
emp3.manager is emp2.
emp4.manager is emp2.
emp5.manager is emp2.

> 1) SELECT UNIQUE manager FROM Employee WHERE lastname == 'emp2Last'
>
> expected result: null

Right.
>
> 2) SELECT manager FROM Employee WHERE lastname == 'emp2Last'
>
> expected result: {null}

Right.
>
> 3) SELECT DISTINCT manager FROM Employee
>
> expected result: {"emp2", null}

I think the expected result is {emp2, null} or {null, emp2} That is,  
a reference to emp2 not the string "emp2" and the order is not  
important.

I think the tests make sense. Thanks.

Craig
>
> Regards,
> Michael
> -- 
> -------------------------------------------------------------------
> Michael Watzek                  Tech@Spree Engineering GmbH
> mailto:mwa.tech@spree.de        Buelowstr. 66
> Tel.:  ++49/30/235 520 36       10783 Berlin - Germany
> Fax.:  ++49/30/217 520 12       http://www.spree.de/
> -------------------------------------------------------------------
>


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