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Thread: Finding multiple events of the same kind

Finding multiple events of the same kind

From
"Leif B. Kristensen"
Date:
I've got two tables:

CREATE TABLE events (   event_id    INTEGER PRIMARY KEY,   tag_fk      INTEGER NOT NULL REFERENCES tags (tag_id),
place_fk   INTEGER NOT NULL REFERENCES places (place_id),   event_date  CHAR(18) NOT NULL DEFAULT '000000003000000001',
 sort_date   DATE NOT NULL DEFAULT '40041024BC',   event_note  TEXT NOT NULL DEFAULT ''
 
);

CREATE TABLE participants (   person_fk   INTEGER NOT NULL REFERENCES persons (person_id),   event_fk    INTEGER NOT
NULLREFERENCES events (event_id) ON DELETE 
 
CASCADE,   is_principal BOOLEAN NOT NULL DEFAULT false,   PRIMARY KEY (person_fk, event_fk)
);

The table "participants" is of course a many-to-many relation 
between "events" and "persons". My problem is that it's entirely 
possible to insert eg. multiple birth events for one person, and I'd 
like to be able to spot these.

I've made this function that will return a birth date, but it will of 
course be somewhat undefined in case of multiple events (tag_fk 
2=birth, 62=stillbirth, 1035="guesstimated" birth).

CREATE OR REPLACE FUNCTION get_pbdate(INTEGER) RETURNS TEXT AS $$
DECLARE   pb_date TEXT;
BEGIN   SELECT event_date INTO pb_date FROM events, participants   WHERE events.event_id = participants.event_fk
ANDparticipants.person_fk = $1       AND events.tag_fk in (2,62,1035)       AND participants.is_principal IS TRUE;
RETURNCOALESCE(pb_date,'000000003000000001');
 
END;
$$ LANGUAGE plpgsql;

The originating database had a field for "primary" event, along with 
some business logic for deciding between multiple events of the same 
type, but I don't want to maintain something like that. I'll rather run 
a report spotting persons with multiple birth events. Any ideas?
-- 
Leif Biberg Kristensen | Registered Linux User #338009
http://solumslekt.org/ | Cruising with Gentoo/KDE

Re: Finding multiple events of the same kind

From
Frank Bax
Date:
At 08:53 AM 6/11/06, Leif B. Kristensen wrote:

>I've got two tables:
>
>CREATE TABLE events (
>     event_id    INTEGER PRIMARY KEY,
>     tag_fk      INTEGER NOT NULL REFERENCES tags (tag_id),
>     place_fk    INTEGER NOT NULL REFERENCES places (place_id),
>     event_date  CHAR(18) NOT NULL DEFAULT '000000003000000001',
>     sort_date   DATE NOT NULL DEFAULT '40041024BC',
>     event_note  TEXT NOT NULL DEFAULT ''
>);
>
>CREATE TABLE participants (
>     person_fk   INTEGER NOT NULL REFERENCES persons (person_id),
>     event_fk    INTEGER NOT NULL REFERENCES events (event_id) ON DELETE
>CASCADE,
>     is_principal BOOLEAN NOT NULL DEFAULT false,
>     PRIMARY KEY (person_fk, event_fk)
>);
>
>The table "participants" is of course a many-to-many relation
>between "events" and "persons". My problem is that it's entirely
>possible to insert eg. multiple birth events for one person, and I'd
>like to be able to spot these.


Something like this should get a list of person_fk values that have more 
than one birth date:

SELECT participants.person_fk, count(participants.person_fk) FROM events, 
participants   WHERE events.event_id = participants.event_fk        AND events.tag_fk in (2,62,1035)   GROUP BY
participants.person_fkHAVING count(participants.person_fk) > 1

Re: Finding multiple events of the same kind

From
"Leif B. Kristensen"
Date:
On Sunday 11. June 2006 15:27, Frank Bax wrote:
>SELECT participants.person_fk, count(participants.person_fk) FROM
> events, participants
>    WHERE events.event_id = participants.event_fk
>         AND events.tag_fk in (2,62,1035)
>    GROUP BY participants.person_fk HAVING
> count(participants.person_fk) > 1

That worked like a charm! Thank you very much!
--
Leif Biberg Kristensen | Registered Linux User #338009
http://solumslekt.org/ | Cruising with Gentoo/KDE

Re: Finding multiple events of the same kind

From
Richard Broersma Jr
Date:
> On Sunday 11. June 2006 15:27, Frank Bax wrote:
> >SELECT participants.person_fk, count(participants.person_fk) FROM
> > events, participants
> >    WHERE events.event_id = participants.event_fk
> >         AND events.tag_fk in (2,62,1035)
> >    GROUP BY participants.person_fk HAVING
> > count(participants.person_fk) > 1
> 
> That worked like a charm! Thank you very much!
> -- 

Also,  you could create a unique column constraint that would prevent multiply instances of the
same person in the participants table.

Regards,

Richard Broersma Jr.

Re: Finding multiple events of the same kind

From
"Leif B. Kristensen"
Date:
On Sunday 11. June 2006 20:36, Richard Broersma Jr wrote:
>Also,  you could create a unique column constraint that would prevent
> multiply instances of the same person in the participants table.

I have considered that as well. But as my front end main view looks like 
a "structured document" in a browser window, ie. with events and their 
associated notes and sources, it's sometimes very convenient to enter 
and view duplicate events. It can be of immense help in a critical 
evaluation of sources. Here's a screenshot of the main view: 
<http://solumslekt.org/temp/exodus1.jpg>
-- 
Leif Biberg Kristensen | Registered Linux User #338009
http://solumslekt.org/ | Cruising with Gentoo/KDE

Re: Finding multiple events of the same kind

From
"Leif B. Kristensen"
Date:
My question and your answer have now become part of a blog entry at my 
site: <http://solumslekt.org/blog/>. Thank you again.
-- 
Leif Biberg Kristensen | Registered Linux User #338009
http://solumslekt.org/ | Cruising with Gentoo/KDE