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]