Thread: DISTINCT ON
Hi, Just quickly, DISTINCT ON - Is that Postgresql only ? Thanks
Don't know. I've seen it elsewhere so it might even be "standard". Chris > -----Original Message----- > From: pgsql-sql-owner@postgresql.org > [mailto:pgsql-sql-owner@postgresql.org]On Behalf Of Rudi Starcevic > Sent: Friday, 13 September 2002 10:50 AM > To: pgsql-sql@postgresql.org > Subject: [SQL] DISTINCT ON > > > Hi, > > Just quickly, DISTINCT ON - Is that Postgresql only ? > Thanks > > > ---------------------------(end of broadcast)--------------------------- > TIP 5: Have you checked our extensive FAQ? > > http://www.postgresql.org/users-lounge/docs/faq.html >
Hi all, although this is not really SQL, but PL/pgSQL, I hope this is the right place to ask. I have written a complex triggers. It works very well. Just now I have realized that I have used the = operater for variable assignments, instead of the := operater. To my suprise, there was no error or warning, and the store procedure works very well! e.g. NEW.someval = rec.someother; works as well as NEW.someval := rec.someother; Can you confirm that both are valid? Can someone explain this? And is it safe to use the former syntax? Best Regards, Michael Paesold
According to a recent thread Re: [SQL] Select the max on a field
Jeff Eckerman said:
>If you don't mind a non-portable feature, DISTINCT ON
>should do what you want. Something like:
>SELECT DISTINCT ON (att_2) att_1, att_2, att_3, att_4
>FROM table
>ORDER BY att_2, att_1 DESC;
>FROM table
>ORDER BY att_2, att_1 DESC;
I couldnt find anything in the docs, but it acording to this it isnt standard
Thanks
Chad
----- Original Message -----
From: "Christopher Kings-Lynne" <chriskl@familyhealth.com.au>
To: "Rudi Starcevic" <rudi@oasis.net.au>; <pgsql-sql@postgresql.org>
Sent: Thursday, September 12, 2002 8:48 PM
Subject: Re: [SQL] DISTINCT ON
> Don't know. I've seen it elsewhere so it might even be "standard".
>
> Chris
>
> > -----Original Message-----
> > From: pgsql-sql-owner@postgresql.org
> > [mailto:pgsql-sql-owner@postgresql.org]On Behalf Of Rudi Starcevic
> > Sent: Friday, 13 September 2002 10:50 AM
> > To: pgsql-sql@postgresql.org
> > Subject: [SQL] DISTINCT ON
> >
> >
> > Hi,
> >
> > Just quickly, DISTINCT ON - Is that Postgresql only ?
> > Thanks
> >
>
> Chris
>
> > -----Original Message-----
> > From: pgsql-sql-owner@postgresql.org
> > [mailto:pgsql-sql-owner@postgresql.org]On Behalf Of Rudi Starcevic
> > Sent: Friday, 13 September 2002 10:50 AM
> > To: pgsql-sql@postgresql.org
> > Subject: [SQL] DISTINCT ON
> >
> >
> > Hi,
> >
> > Just quickly, DISTINCT ON - Is that Postgresql only ?
> > Thanks
> >
Michael, > although this is not really SQL, but PL/pgSQL, I hope this is the right > place to ask. This is the right place. > I have written a complex triggers. It works very well. Just now I have > realized that I have used the = operater for variable assignments, instead > of the := operater. To my suprise, there was no error or warning, and the > store procedure works very well! > > e.g. > NEW.someval = rec.someother; > works as well as > NEW.someval := rec.someother; > > Can you confirm that both are valid? Can someone explain this? > And is it safe to use the former syntax? I'm very surprised, too. The "=" syntax is not per spec; my guess is, somebody coded in compatibility for DB conversion purposes and left it there. Jan? Tom? -- -Josh BerkusAglio Database SolutionsSan Francisco
Josh Berkus wrote:
> I'm very surprised, too. The "=" syntax is not per spec; my guess is,
> somebody coded in compatibility for DB conversion purposes and left it there.
> Jan? Tom?
>
I also noticed this the other day while messing with the plpgsql lexer:
/* ---------- * The keyword rules * ---------- */
:= { return K_ASSIGN; }
= { return K_ASSIGN; }
This code goes back to the original scan.l from 1998. I'm guessing it has
always worked, but was never documented -- but I've been known to be wrong
sometimes ;-). Hopefully Jan will chime in.
Joe
Josh Berkus wrote: > > Michael, > > > although this is not really SQL, but PL/pgSQL, I hope this is the right > > place to ask. > > This is the right place. > > > I have written a complex triggers. It works very well. Just now I have > > realized that I have used the = operater for variable assignments, instead > > of the := operater. To my suprise, there was no error or warning, and the > > store procedure works very well! > > > > e.g. > > NEW.someval = rec.someother; > > works as well as > > NEW.someval := rec.someother; > > > > Can you confirm that both are valid? Can someone explain this? > > And is it safe to use the former syntax? > > I'm very surprised, too. The "=" syntax is not per spec; my guess is, > somebody coded in compatibility for DB conversion purposes and left it there. > Jan? Tom? Er ... I don't recall completely, maybe it was more compatibility to my own lazyness ;-/ (typing a colon means Shift-and-semicolon ... that's 2 saved keystrokes per assignment ... what do you think where I save all the keystrokes I need to write email like this?). Jan -- #======================================================================# # It's easier to get forgiveness for being wrong than for being right. # # Let's break this rule - forgive me. # #================================================== JanWieck@Yahoo.com #
Jan, > Er ... I don't recall completely, maybe it was more compatibility > to my own lazyness ;-/ (typing a colon means Shift-and-semicolon > ... that's 2 saved keystrokes per assignment ... what do you > think where I save all the keystrokes I need to write email like > this?). Hmmm. Well, as long as it doesn't cause any problems, why not keep it? Surely if it caused bugs, we'd have heard by now. -- -Josh BerkusAglio Database SolutionsSan Francisco