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From Jeremy Boynes <jboy...@apache.org>
Subject Re: INTERSECT and EXCEPT Design
Date Mon, 28 Feb 2005 18:14:48 GMT
Jack Klebanoff wrote:
> RPost wrote:
> 
>> >Jack Klebanoff wrote:
>>  
>> >The syntax is (roughly):
>>
>> />queryExpression/ INTERSECT [ALL] /queryExpression/
>> />queryExpression/ EXCEPT [ALL] /queryExpression/
>>
>> Although DISTINCT is implicit if ALL is not specified the SQL standard 
>> also allows the DISTINCT operator to be specified explicitly. Would it 
>> make sense to do that in Derby also?
>>
>>      INTERSECT [ALL | DISTINCT] and EXCEPT [ALL | DISTINCT]
>>
> Other relational databases do not all support the "DISTINCT" keyword, so 
> applications that use it will not be portable.
> 

It is part of the spec so there is no reason not to support it; people 
seeking greater portability between (non-compliant) databases simply 
don't need to use it.

> That being said, I think that adding the "DISTINCT" keyword would be a 
> good project for a neophyte who wants to get his or her feet wet in the 
> Derby parser.
> 

I'll take it on as a first real commit (vs. patch).

--
Jeremy

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