wiki-archive/twiki/data/ABCD/InventoryRequest.txt,v

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date 2007.01.09.00.00.00; author MoinMoin; state Exp;
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@The inventory request is supposed to return a distinct list of a list of concepts.
Additionally one may request to count the number of records for each distinct combination of concepts.
---+++ Problems accountered
* In this request there is no natural "root" table. All concepts are equal and therefore a left join to link the tables is not appropiate. A regular join is implemented. This brings the following problems:
* It is impossible to retrieve NULLs in the response
* If I ask for example just for distinct specimen names in the database, there is no relation to a specimen in the query anymore and ALL names will be returned, regardless if there is a specimen belonging to it. To prevend this the query must specify a filter with for example: SPECIMEN_ID IS NOT NULL. This forces the query generator to include the specimen table and to make sure there is a specimen attached to a name.
* Multiple db attributes mapped to a single concept. It should be possible to map several db attributes or literals to a concept. For example some databases have 2 columns for collector1 and collector2 which both map to the concept "collector".
* Is it possible to generate a proper SQL in this case?
* Are UNIONS needed?
* how can the distinct combinations be counted?
* *!!! Currently an error is raised if an inventory is done on a concept that has several mappings !!!*
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