From: Gergely Czuczy <phoemix@harmless.hu>
To: Michael Stephenson <mstephenson@tirin.openworld.co.uk>
Cc: Kenneth Suralta <ksuralta@ntsp.nec.co.jp>
Cc: pgsql-interfaces@postgresql.org
Subject: Re: help on SQL
Date: Wed, 21 Apr 2004 12:21:32 +0200 (CEST)
Message-ID: <Pine.LNX.4.44.0404211219360.30186-100000@localhost> (raw)
In-Reply-To: <Pine.LNX.4.58.0404210952400.29792@tirin.openworld.co.uk>
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
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> 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
> >
> > --
> >
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> > Bye,
> >
> > Gergely Czuczy
> > mailto: phoemix@harmless.hu
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> >
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Bye,
Gergely Czuczy
mailto: phoemix@harmless.hu
PGP: http://phoemix.harmless.hu/phoemix.pgp
"Wish a god, a star, to believe in,
With the realm of king of fantasy..."
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To: pgsql-interfaces@postgresql.org
Cc: phoemix@harmless.hu, mstephenson@tirin.openworld.co.uk, ksuralta@ntsp.nec.co.jp
Subject: Re: help on SQL
In-Reply-To: <Pine.LNX.4.44.0404211219360.30186-100000@localhost>
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