Hello,
just some more word :
> > In my opinion, these queries make the same :
> > SELECT id FROM article WHERE id=(SELECT MAX(id) FROM article);
> > SELECT MAX(id) FROM article;
> >
> > but the latter one is much more simple and you do not overload your pg.
> > (by the way, I think id = (SELECT ...) isn't handled gracefully.)
>
> Hi, although I agreee with the first part: the subselect is redundat in
> this case, I don't understand de second one. The subselect will return one
> value, or am I wrong? So, I think the operator = will be correct, or not?
I mean the second sentence that I don't think the planner/optimizer is so clever to reduce the former query to the latter one.
You're right the sublselect will return one value, but as far as I know this value should be interpreted as a set of one value (because of the select).
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