Il Thursday 15 November 2007 23:08:10 Richard Huxton ha scritto:
> Reg Me Please wrote:
> > Il Thursday 15 November 2007 20:28:17 hai scritto:
> >> Reg Me Please wrote:
> >>> In my opinion I would say it's more a problem with the syntax checker
> >>> that with the planner ("semantics" in my lingo). But I could be wrong.
> >>
> >> Well, what it won't let you do is have a subquery in the LIMIT clause.
> >> That's probably due to a combination of:
> >> 1. The spec probably says something about it
> >> 2. There is an obvious approach involving functions/prepared queries
> >> 3. You're the first person to have asked for it.
> >>
> >> Now if you can get a couple of hundred to join you at #3, you might have
> >> a feature request :-)
> >
> > Hmmm ...
> >
> > It also works with STABLE functions, though.
>
> Well, STABLE means the value won't change during the query.
>
> > 1. Unluckily I've been too lazy t read the specs.
>
> A wise choice. They're not my idea of fun either.
>
> > 2. I am not willing to put subqueries there, just need to drive the
> > "windowing" mechanism by means of a second table (limoff).
>
> And how do you plan to get information from limoff unless it's by a
> subquery?
>
> > 3. Dont' think so :)
> >
> > The solution I'm using now (two functions) allows for really variable
> > limit and offset argument. It's just UGLY to write. But it works.
> > And if it works it should be made available in a easier way (unless the
> > specs advise otherwhise) with a simple table field (or a function
> > parameter) as the argument for the LIMIT and for the OFFSET. Maybe with a
> > huge warning about possible drawbacks with the query planner.
>
> But you're back to subqueries here and the possibility of multiple
> values from limoff. Even if you do something like:
> SELECT ... LIMIT (SELECT l FROM limoff LIMIT 1)
> That doesn't guarantee you one row - you might get zero.
>
> > I'll check whether I can drop a feature request, even without undreds of
> > fellows.
>
> Hey, anyone can request a feature. You're more likely to get it
> implemented with a mix of coding skills, money and user-demand though.
You are right: in SQl anything is a query. So I'll close this.
The thing is doable and working. The syntax parser doesn't allow it,
maybe because of a bug, but there's a workaround. This's enough for myself.
--
Reg me Please
