CREATE OR REPLACE TRIGGER  "KLUBY_T2" 
BEFORE
insert or update or delete on "KLUBY"
for each row
begin
 if :NEW.ID_KLUBU is null then 
    :NEW.ID_KLUBU := KLUBY_SEQ.nextval; 
  end if;
end;

/
ALTER TRIGGER  "KLUBY_T2" ENABLE
/