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Posted to derby-dev@db.apache.org by Bryan Pendleton <bp...@gmail.com> on 2010/04/28 03:23:27 UTC

Re: USING behavior

> SELECT * FROM (T1 JOIN T2 USING (A)) JOIN T3 USING (A)
> 
> The columns returned by the first join operator, T1 JOIN T2 USING (A),
> are: A, T1.B, T1.C, T2.B, T2.C (note: the column in the USING clause is
> only returned once, even though it exists both in T1 and T2)

That's a subtle aspect of USING that I wasn't previously aware of.

Thanks much for the clear explanation of the feature's behavior!

bryan