Re: [Gnumed-devel] Getting Canadian drug data into FreeDiams

[Karsten Hilbert]

On Fri, Feb 19, 2010 at 08:40:13AM -0800, Jim Busser wrote:

> On account of the above (attempted) selection drawing from 4 tables, 
> apparently you have to set a condition that will result in one record per 
> desired entity, which is why a person would above specify that for each drug 
> in the first table, you want one matching value in a related table (otherwise 
> you get a Cartesian cross-product such that if you had 4 records in source 
> table A1, and 4 records in source table A2, you would end up with 16 records 
> INSERTed INTO.
> 
> So I did not know whether in doing the SELECT FROM, it would be proper and 
> supported to try a statement like
>       WHERE A1.DRUG_CODE = A2.DRUG_CODE AND A1.DRUG_CODE=A3.DRUG_CODE AND 
> A1.DRUG_CODE=A4.DRUG_CODE

Ah, I see. Well, the WHERE conditions apply to each row of
the full join, so, yes, that's OK.

Karsten
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