oracle 簡單觸發器

create   or   replace   trigger   trg_envparking 
before   insert   on   app_envparking 
for   each   row 
begin 
select   seq_envparking.nextval   into   :new.incid   from   dual; 
select   sysdate   into   :new.CONSTDATE   from   dual;
select   sysdate   into   :new.UPDATEDATE   from   dual;
end;