hello,

i have following table:
id      b_stueck        b_name          b_preis         b_summe
        (units)                         (price)         (sum)

i want b_summe automatically be calculated, therefore i use 
following trigger:
CREATE RULE summieren AS  ON INSERT TO t_bestand DO UPDATE t_bestand SET
b_summe=(b_stueck*b_preis) FROM t_bestand 

after all, i get following result:

webliste=# INSERT INTO t_bestand(b_stueck, b_name, b_preis)
VALUES(1,'CD','20'); 
INSERT 0 2
webliste=# SELECT * FROM t_bestand;
 id | b_stueck |   b_name   | b_preis | b_summe  
----+----------+------------+---------+----------
  1 |        3 | Festplatte | DM49,00 | DM147,00
  2 |        4 | Disketten  | DM45,00 | DM180,00
  5 |        1 | CD         | DM20,00 |         
  6 |        1 | CD         | DM20,00 |         
(4 rows)


the row is doubled,

any hints why and how the b_summe be calculated automatically??

thanks in advance
--
Hakan Kuecuekyilmaz FHT-Esslingen University of Applied Sciences,
Germany
[EMAIL PROTECTED]

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