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From | Zinchik |
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Msg-id | 13043476738925@MEGAHERTZ.NET Whole thread Raw |
List | pgsql-docs |
At 11:00 PM 2/18/99 -0500, you wrote: > >pgsql-docs-digest Thursday, February 18 1999 Volume 01 : Number 411 > > > >Index: > >A little nitpick correction >Can this be added to manual? > >---------------------------------------------------------------------- > >Date: Thu, 18 Feb 1999 15:34:33 +0100 >From: Hans de Goede <j.w.r.degoede@et.tudelft.nl> >Subject: A little nitpick correction > >Hi all, > >Well you said you wanted to know any errors int he docs: >In the tutorial chapter 3 getting started: >in Managing a database: >The followign example code is given: >- --- >% psql mydb > >You will be greeted with the following message: > >Welcome to the POSTGRESQL interactive sql monitor: > Please read the file COPYRIGHT for copyright terms of POSTGRESQL > > type \? for help on slash commands > type \q to quit > type \g or terminate with semicolon to execute query > You are currently connected to the database: template1 > >mydb=> >- --- >Template 1 should of course be mydb over here. >since I'm just learning postgress I'm digging through the tutorial. I'll >lett you know >if I find more mistakes. > >Regards, >Hans > >------------------------------ > >Date: Thu, 18 Feb 1999 20:56:06 -0500 >From: Fred Wilson Horch <fhorch@ecoaccess.org> >Subject: Can this be added to manual? > >I found this to be an extremely useful message to help understand how >aggregates and joins work. Can this be included in the manual for 6.5? > >In particular, the following commands would be nice to use as examples >in the chapters on joins and using aggregates: > >> -- all that have ever existed (most recent) >> SELECT * from stuff* s1 WHERE d = (SELECT MAX(d) FROM stuff* s2 WHERE >> s1.id = s2.id); >> -- records @ or before '2/2/1999 13:50:00' >> SELECT * from stuff* s1 WHERE d = (SELECT MAX(d) FROM stuff* s2 WHERE >> s1.id = s2.id and s2.d <= '2/2/1999 13:50:00'); > >Just a suggestion, >- --Fred > >Full message: > >> RE: [GENERAL] Missing features ? >> >> From: "Jackson, DeJuan" <djackson@cpsgroup.com> >> To: Remigiusz Sokolowski <rems@gdansk.sprint.pl>, Joerg >> Huettmann <joerg.huettmann@informatik.tu-chemnitz.de> >> Subject: RE: [GENERAL] Missing features ? >> Date: Tue, 2 Feb 1999 13:55:39 -0600 >> >> [Time travel] was depreciated because of it's high overhead verses it's >> utility. In other words not enough people were using it to make it >> worth the cost in everyone's database. There are many way that you can >> design the same type of system in your own database. I suggest using >> inheritance and RULES. Example (assuming id is PRIMARY KEY): >> >> CREATE TABLE stuff ( >> id INT, >> t TEXT, >> d DATETIME DEFAULT(DATETIME(NOW())) >> ); >> CREATE UNIQUE INDEX stuff_pkey ON stuff(id); >> CREATE TABLE old_stuff () INHERITS (stuff); >> CREATE RULE del_stuff AS ON DELETE TO stuff DO >> INSERT INTO old_stuff SELECT old.*; >> CREATE RULE up_stuff AS ON UPDATE TO stuff DO >> INSERT INTO old_stuff SELECT old.*; >> INSERT INTO stuff (id, t) VALUES (1, 'Hello there.'); >> INSERT INTO stuff (id, t) VALUES (2, 'Hi there.'); >> INSERT INTO stuff (id, t) VALUES (3, 'Hello there again.'); >> INSERT INTO stuff (id, t) VALUES (4, 'Hi there once more.'); >> INSERT INTO stuff (id, t) VALUES (5, 'Hello there.'); >> UPDATE stuff SET d=now(), t='Hi' WHERE t='Hello there.'; >> DELETE FROM stuff WHERE id=2; >> DELETE FROM stuff WHERE id=5; >> -- current snapshot >> SELECT * from stuff; >> -- all that have ever existed (most recent) >> SELECT * from stuff* s1 WHERE d = (SELECT MAX(d) FROM stuff* s2 WHERE >> s1.id = s2.id); >> -- records @ or before '2/2/1999 13:50:00' >> SELECT * from stuff* s1 WHERE d = (SELECT MAX(d) FROM stuff* s2 WHERE >> s1.id = s2.id and s2.d <= '2/2/1999 13:50:00'); >> >> I think you get the idea. If you want to store the date an item was >> delete/updated rather than when it was inserted the rules become: >> CREATE RULE del_stuff AS ON DELETE TO stuff DO >> INSERT INTO old_stuff SELECT old.id, old.t, datetime(now()); >> CREATE RULE up_stuff AS ON UPDATE TO stuff DO >> INSERT INTO old_stuff SELECT old.id, old.t, datetime(now()); >> >> Hope this helps, >> -DEJ > >------------------------------ > >End of pgsql-docs-digest V1 #411 >******************************** > http://www.zinchik.net * Tell a man that there are 400 billion stars and he'll believe you. Tell him a bench has wet paint and he has to touch it.
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