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Subject: Re: [regrep] Inner joins using Entry level SQL-1992

Richard Martell wrote:

> Diego Ballve wrote:
>> Hi Richard,
>> What experience has shown is that we need a LEFT JOIN for some cases, 
>> for instance you have this kind of parameterized query:
>> SELECT * FROM RegistryObject ro, Name_ nm, Description d
>> WHERE nm.parent = ro.id AND '$name' = nm.value
>> AND d.parent = ro.id AND '$desc' = d.value
>> Now, since name and description are not mandatory, any RO that does 
>> not have name/desc will be cut out of that result set. Imagine that 
>> you want to search with $name = 'MyObject' and $desc = '%'. You won't 
>> get all objects named 'MyObject', but only the ones that have any 
>> description.
>> This would return also objects without name/desc:
>> SELECT * FROM RegistryObject ro
>> LEFT JOIN Name_ nm ON nm.parent = ro.id
>> LEFT JOIN Description d ON d.parent = ro.id
>> WHERE '$name' = nm.value AND '$desc' = d.value
>> Regards,
>> Diego
> Then this would definitely call for an "upgrade" to Intermediate SQL
> if this were to be acceptable as a naked SQL query (vs. generated from
> some filter query--is this possible?). Most--if not all--commercial 
> and leading open source relational databases will handle such queries 
> these
> days, so it doesn't really pose a technical hurdle. Or the implementer
> does some pre-processing to make it palatable. If the backend chokes,
> just throw up an exception.
> I would consider this a minor enhancement. Perhaps Diego can submit
> this comment ;-)

Diego and I can work offline to get the comment submitted. Thanks.


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