Fórum Trigger com sequence #28296

CREATE OR REPLACE TRIGGER TRG_EXEMPLO_B_I
BEFORE INSERT 
ON TABELA_EXEMPLO
REFERENCING NEW AS NEW OLD AS OLD
FOR EACH ROW
DECLARE
  v_chave TABELA_EXEMPLO.chave¬type;
BEGIN
  if :new.chave is null then
      v_chave := exemplo_seq.nextval; 
  end if;
END;
/