> 
> First, this list is not right place to ask about 6.3 features :)
> 2nd, subselects within UPDATE are supported.

They are?  I thought he wanted to do:

	update test set x = (select y from taby)

I didn't think we supported that.  Can you confirm that?
 
> 3rd, there will be separate select (better say - separate re-scan of
> subquery' plan) for each parent row (I assume that you talk about 
> correlated subqueries) but this will be more efficient than using 
> SQL-funcs which do _initialization_, scannig, _closing_ of query' plan
> for each parent row. When using subqueries performance will be
> near the same as for performing Nestloop join.

Good.

-- 
Bruce Momjian                          |  830 Blythe Avenue
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Wed, 25 Feb 1998 09:28:10 -0500 (EST)
Bruce Momjian <maillist@candle.pha.pa.us>
Re: [QUESTIONS] How fully will subselects be implemented?
> 
> Herouth Maoz wrote:
> > 
> > I'm developing a new app, and I constantly run into the need of updating
> > things by data in related columns.
> > 
> > Since UPDATE doesn't syntatctically support joins, this means that
> > subselects in UPDATE are a real must.

OK, now I see he only wants the subquery in the where clause.  That
clearly does work.

-- 
Bruce Momjian                          |  830 Blythe Avenue
maillist@candle.pha.pa.us              |  Drexel Hill, Pennsylvania 19026
  +  If your life is a hard drive,     |  (610) 353-9879(w)
  +  Christ can be your backup.        |  (610) 853-3000(h)

Wed, 25 Feb 1998 09:29:03 -0500 (EST)
Bruce Momjian <maillist@candle.pha.pa.us>
Re: [QUESTIONS] How fully will subselects be implemented?
Bruce Momjian wrote:
> 
> >
> > First, this list is not right place to ask about 6.3 features :)
> > 2nd, subselects within UPDATE are supported.
> 
> They are?  I thought he wanted to do:
> 
>         update test set x = (select y from taby)
> 
> I didn't think we supported that.  Can you confirm that?

Oh, this is not supported, sorry.
And select a, (select b from tab2) from tab1 and so on...

Vadim

Wed, 25 Feb 1998 22:59:35 +0700
"Vadim B. Mikheev" <vadim@sable.krasnoyarsk.su>
Re: [QUESTIONS] How fully will subselects be implemented?