> > Could you not rewrite this as a simple join though?
>
> Hmmm, I don't see how. Then again, I'm pretty much the village
> idiot w.r.t. SQL...
>
> The inner select is locating a set of (2049) ids (actually from
> the same table, since 'attributes' is just a view into
> 'attributes_table'). The outer select is then locating all
> records (~30-40K) that have any of those ids. Is that really
> something a JOIN could be used for?
This may be a question for SQL theoretists, but I don't think I've ever
run across a query with a 'where in' clause that couldn't be written
as a join. I think linguistically 'where in' may even be a special
case of 'join'.
Yet another question for the theoretists: Would it be possible to optimize
a 'where in' query by rewriting it as a join?
--
Mike Nolan
