Orakel; Zeilen pro Spaltenwert begrenzen

Dies kann anstelle Ihres Triggers funktionieren:

CREATE MATERIALIZED VIEW mv_my
BUILD IMMEDIATE
REFRESH FAST ON COMMIT AS
SELECT POSTALCODE, COUNT(*) AS cnt FROM TEST GROUP BY POSTALCODE
/

ALTER TABLE mv_my ADD CHECK(cnt < 2)
/

Lass es mich wissen.Prost,

Sebas