PL/pgSQL und FOUND

Grüezi ;-)

Ich habe ein Problem mit PL/pgSQL und der Variablen FOUND. Folgendes
klappt bei mir nicht:

...
PERFORM * FROM person WHERE name = 'Florian';
IF NOT FOUND THEN
...
ELSE
...
END IF;
...

-------------------------------------------------------------------------

Ich habe mal die ganze Funktion gepostet:

BEGIN;

CREATE
FUNCTION geonames.update_or_create_metadata(BIGINT, INTEGER, TEXT,
TEXT, TEXT)
RETURNS void AS $BODY$

DECLARE

geoobj ALIAS FOR $1;
mt ALIAS FOR $2;
inf ALIAS FOR $3;
s ALIAS FOR $4;
d ALIAS FOR $5;

ret TEXT;

BEGIN

PERFORM md.information
FROM geonames.metadata md
WHERE (md.fid_geoobject = geoobj) AND (md.fid_metatype = mt);

IF NOT FOUND THEN
EXECUTE 'INSERT INTO geonames.metadata VALUES ( ' || geoobj || ',
' || mt || ', ''' || inf || ''', ''' || s || ''', ''' || d ||''');';
ELSE
EXECUTE 'UPDATE geonames.metadata SET information = ''' ||
inf || ''', source = ''' || s || ''', dateofcapture =
''' || d || ''' WHERE (fid_geoobject = ' ||
geoobj || ') AND (fid_metatype = ' || mt || ');';
END IF;

RETURN;

END;
$BODY$ LANGUAGE plpgsql;

COMMIT;

-------------------------------------------------------------------------

Die Tabelle:

CREATE TABLE geonames.metadata (

fid_metatype INTEGER,
fid_geoobject BIGINT,

information TEXT NOT NULL,
source TEXT,
dateofcapture TEXT,

PRIMARY KEY (fid_geoobject, fid_metatype),

FOREIGN KEY (fid_metatype) REFERENCES geonames.metatype
ON DELETE CASCADE,
FOREIGN KEY (fid_geoobject) REFERENCES geonames.geoobject
ON DELETE CASCADE

);

-------------------------------------------------------------------------

Eigendlich sollte folgenden Aufruf keinen Error geben, da ja UPDATE und
nicht INSERT aufgerufen werden:

SELECT geonames.update_or_create_metadata(16, 22, 'xyz', 'b', '');

ERROR: duplicate key violates unique constraint "metadata_pkey"
KONTEXT: SQL statement "INSERT INTO geonames.metadata VALUES ( 16, 22,
'xyz', 'b', '');"
PL/pgSQL function "update_or_create_metadata" line 19 at execute statement

-------------------------------------------------------------------------

Ich hoffe jemand kann mir helfen? Ich bin ziemlich ratlos und nach 2
Stunden recherche am Ende meines Lateins.

Vielen Dank bereits im Voraus.
Freundliche Grüsse
Thomas Zuberbühler

--
Thomas Zuberbühler
http://www.zubi.li

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