Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.databases.postgresql > #334

Re: Joining two tables using *two* columns (instead of one)

Path csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!news.glorb.com!news.netfront.net!reversiblemaps.ath.cx!not-for-mail
From Jasen Betts <jasen@xnet.co.nz>
Newsgroups comp.databases.postgresql
Subject Re: Joining two tables using *two* columns (instead of one)
Date 5 Apr 2012 21:20:41 GMT
Organization Dis (not Dat) Organisation
Lines 25
Message-ID <jll2b9$9p4$1@reversiblemaps.ath.cx> (permalink)
References <4f7d9c45$0$1745$426a34cc@news.free.fr> <jlkaa5$9ii$1@dont-email.me>
NNTP-Posting-Host 118.90.123.29
Mime-Version 1.0
Content-Type text/plain; charset=UTF-8
Content-Transfer-Encoding 8bit
X-Trace adenine.netfront.net 1333661440 37667 118.90.123.29 (5 Apr 2012 21:30:40 GMT)
X-Complaints-To news@netfront.net
NNTP-Posting-Date Thu, 5 Apr 2012 21:30:40 +0000 (UTC)
X-Face ?)Aw4rXwN5u0~$nqKj`xPz>xHCwgi^q+^?Ri*+R(&uv2=E1Q0Zk(>h!~o2ID@6{uf8s;a +M[5[U[QT7xFN%^gR"=tuJw%TXXR'Fp~W;(T"1(739R%m0Yyyv*gkGoPA.$b,D.w:z+<'"=-lVT?6 {T?=R^:W5g|E2#EhjKCa+nt":4b}dU7GYB*HBxn&Td$@f%.kl^:7X8rQWd[NTc"P"u6nkisze/Q;8 "9Z{peQF,w)7UjV$c|RO/mQW/NMgWfr5*$-Z%u46"/00mx-,\R'fLPe.)^
User-Agent slrn/pre1.0.0-18 (Linux)
Xref csiph.com comp.databases.postgresql:334

Show key headers only | View raw

On 2012-04-05, Lennart Jonsson <erik.lennart.jonsson@gmail.com> wrote:
>> 
>> SELECT id, prob1.value AS p1, prob2.value AS p2
>>   FROM subnet
>>   LEFT OUTER JOIN probes AS prob1 ON prob1.id=probe1
>>   LEFT OUTER JOIN probes AS prob2 ON prob2.id=probe2
>>   WHERE probe1 IS NOT NULL AND probe2 IS NOT NULL;
>
> Without giving it to much thought, this should be equal with:
>
> SELECT id, prob1.value AS p1, prob2.value AS p2
> FROM subnet
> JOIN probes AS prob1
>     ON  prob1.id=probe1
> JOIN probes AS prob2
>     ON prob2.id=probe2;

No, that query may return different results, it won't return rows 
where subnet.probe1 or subnet.probe2 have do not have a matches in 
the probes table

-- 
⚂⚃ 100% natural

--- Posted via news://freenews.netfront.net/ - Complaints to news@netfront.net ---

Back to comp.databases.postgresql | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

Joining two tables using *two* columns (instead of one) Mateusz <no@spam.please> - 2012-04-05 15:21 +0200
  Re: Joining two tables using *two* columns (instead of one) Lennart Jonsson <erik.lennart.jonsson@gmail.com> - 2012-04-05 16:30 +0200
    Re: Joining two tables using *two* columns (instead of one) Mateusz <no@spam.please> - 2012-04-05 18:01 +0200
      Re: Joining two tables using *two* columns (instead of one) Robert Klemme <shortcutter@googlemail.com> - 2012-04-05 23:16 +0200
        Re: Joining two tables using *two* columns (instead of one) Mladen Gogala <gogala.mladen@gmail.com> - 2012-04-06 01:00 +0000
          Re: Joining two tables using *two* columns (instead of one) Jasen Betts <jasen@xnet.co.nz> - 2012-04-06 04:12 +0000
            Re: Joining two tables using *two* columns (instead of one) Mladen Gogala <gogala.mladen@gmail.com> - 2012-04-06 04:44 +0000
              Re: Joining two tables using *two* columns (instead of one) Robert Klemme <shortcutter@googlemail.com> - 2012-04-06 14:17 +0200
                Re: Joining two tables using *two* columns (instead of one) Mladen Gogala <gogala.mladen@gmail.com> - 2012-04-08 19:01 +0000
    Re: Joining two tables using *two* columns (instead of one) Jasen Betts <jasen@xnet.co.nz> - 2012-04-05 21:20 +0000
      Re: Joining two tables using *two* columns (instead of one) Lennart Jonsson <erik.lennart.jonsson@gmail.com> - 2012-04-06 09:30 +0200
        Re: Joining two tables using *two* columns (instead of one) Jasen Betts <jasen@xnet.co.nz> - 2012-04-06 23:42 +0000
        Re: Joining two tables using *two* columns (instead of one) Lennart Jonsson <erik.lennart.jonsson@gmail.com> - 2012-04-08 20:39 +0200
  Re: Joining two tables using *two* columns (instead of one) Mladen Gogala <gogala.mladen@gmail.com> - 2012-04-05 19:48 +0000
    Re: Joining two tables using *two* columns (instead of one) Mladen Gogala <gogala.mladen@gmail.com> - 2012-04-05 19:50 +0000
    Re: Joining two tables using *two* columns (instead of one) Mateusz <no@spam.please> - 2012-04-06 09:13 +0200
  Re: Joining two tables using *two* columns (instead of one) Jasen Betts <jasen@xnet.co.nz> - 2012-04-05 21:28 +0000
    Re: Joining two tables using *two* columns (instead of one) Mateusz <no@spam.please> - 2012-04-06 09:00 +0200
      Re: Joining two tables using *two* columns (instead of one) Jasen Betts <jasen@xnet.co.nz> - 2012-04-06 23:38 +0000
  Re: Joining two tables using *two* columns (instead of one) Mateusz <no@spam.please> - 2012-04-06 08:48 +0200
    Re: Joining two tables using *two* columns (instead of one) Robert Klemme <shortcutter@googlemail.com> - 2012-04-06 14:33 +0200
      Re: Joining two tables using *two* columns (instead of one) Mladen Gogala <gogala.mladen@gmail.com> - 2012-04-11 03:21 +0000
    Re: Joining two tables using *two* columns (instead of one) Torsten Kirschner <torsten.kirschner@gmail.com> - 2012-04-10 05:58 +0200
      Re: Joining two tables using *two* columns (instead of one) Fredrik Jonson <fredrik@jonson.org> - 2012-04-10 08:53 +0000
        Re: Joining two tables using *two* columns (instead of one) Torsten Kirschner <torsten.kirschner@gmail.com> - 2012-04-11 00:06 +0200
          Re: Joining two tables using *two* columns (instead of one) Robert Klemme <shortcutter@googlemail.com> - 2012-04-12 20:38 +0200

csiph-web