Skip site navigation (1) Skip section navigation (2)

Re: help on SQL

From: Gergely Czuczy <phoemix(at)harmless(dot)hu>
To: Michael Stephenson <mstephenson(at)tirin(dot)openworld(dot)co(dot)uk>
Cc: Kenneth Suralta <ksuralta(at)ntsp(dot)nec(dot)co(dot)jp>,<pgsql-interfaces(at)postgresql(dot)org>
Subject: Re: help on SQL
Date: 2004-04-21 10:21:32
Message-ID: Pine.LNX.4.44.0404211219360.30186-100000@localhost (view raw or flat)
Thread:
Lists: pgsql-interfaces
hello

what you have done is not the thing that was asked. you've retrieved every
row that has a spacial value(data-1 %3). the request was to retrieve every
3rd row. the difference is that, the 'every Nth' row has nothing to do
with the value of any field in the row. try to retrieve every Nth row from
a query where there are no integer values, only timestamps and string. or
try to do your method where the integer value is not continous.

On Wed, 21 Apr 2004, Michael Stephenson wrote:

> test=# create table data (data int);
> CREATE
> test=# insert into data values(1);
> INSERT 3531768 1
> test=# insert into data values(2);
> INSERT 3531769 1
> test=# insert into data values(3);
> INSERT 3531770 1
> test=# insert into data values(4);
> INSERT 3531771 1
> test=# insert into data values(5);
> INSERT 3531772 1
> test=# insert into data values(6);
> INSERT 3531773 1
> test=# insert into data values(7);
> INSERT 3531774 1
> test=# select * from data where (data - 1) % 3 = 0;
>  data
> ------
>     1
>     4
>     7
> (3 rows)
>
> test=#
>
> HTH
>
> Michael
>
> Web Applications Developer
> Open World Ltd, 11 Riverside Court, Riverside Road, Bath, BA2 3DZ.
> Tel: +44 1225 444950  Fax: +44 1225 336738  http://www.openworld.co.uk/
>
> CONFIDENTIALITY NOTICE
> The information contained in this message is confidential, intended only for
> the use of the individual or the entity named as recipient. If the reader of
> this message is not that recipient, you are notified that any
> dissemination,
> distribution or copy of this message is strictly prohibited. If you have
> received this message in error, please immediately notify us by telephone on
> the number above. Your co-operation is appreciated.
>
> On Wed, 21 Apr 2004, Kenneth Suralta wrote:
>
> > hi gergely,
> >
> > thanks for replying..
> > what i mean is supposing there is a table with the following rows:
> >
> >  data
> > -----
> > 1
> > 2
> > 3
> > 4
> > 5
> > 6
> > 7
> >
> > is it possible to get every other N-row in the table?
> > example, if N is 3.
> > data
> > -----
> > 1
> > 4
> > 7
> >
> > thanks,
> > kenneth
> >
> >
> >
> > Gergely Czuczy wrote:
> >
> >  On Wed, 21 Apr 2004, Kenneth Suralta wrote:
> >
> >
> >
> >  hello everyone,
> >
> > is it possible to get every other row in the table?
> > like for example:
> > data
> > -----
> > 1
> > 2
> > 3
> > 4
> > 5
> > 6
> > 7
> >
> >
> >  SELECT t.fields FROM table t WHERE data NOT IN (SELECT t2.data FROM table
> >  t2 WHERE some_whereclause);
> >
> > it will select these rows which ones are not in the subquery. but you can
> > do it simply by getting the negate of the whereclause...
> >
> >
> >  Is it possible to have this result (interval of 3)?
> >
> > result
> > ------
> > 1
> > 4
> > 7
> >
> >
> >  i don't see what you mean. please describe it.
> >
> >
> >  thanks,
> > kenneth
> >
> > --
> >
> >
> >
> > ---------------------------(end of broadcast)---------------------------
> > TIP 4: Don't 'kill -9' the postmaster
> >
> >
> >
> >  Bye,
> >
> > Gergely Czuczy
> > mailto: phoemix(at)harmless(dot)hu
> > PGP: http://phoemix.harmless.hu/phoemix.pgp
> >
> > "Wish a god, a star, to believe in,
> > With the realm of king of fantasy..."
> >
> >
> > ---------------------------(end of broadcast)---------------------------
> > TIP 2: you can get off all lists at once with the unregister command
> >     (send "unregister YourEmailAddressHere" to majordomo(at)postgresql(dot)org)
> >
> >
> >
> >
> >
> > --
> > [IMAGE]
> >
> >
>
> ---------------------------(end of broadcast)---------------------------
> TIP 7: don't forget to increase your free space map settings
>


Bye,

Gergely Czuczy
mailto: phoemix(at)harmless(dot)hu
PGP: http://phoemix.harmless.hu/phoemix.pgp

"Wish a god, a star, to believe in,
With the realm of king of fantasy..."


In response to

Responses

pgsql-interfaces by date

Next:From: Michael StephensonDate: 2004-04-21 10:38:25
Subject: Re: help on SQL
Previous:From: Michael StephensonDate: 2004-04-21 09:54:10
Subject: Re: help on SQL

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group