db2中 trigger 怎么写

oracle中：
CREATE OR REPLACE TRIGGER te_acpt_bill_batch_insert_tg BEFORE INSERT ON te_acpt_bill_batch FOR EACH ROW
BEGIN
:new.update_dt := to_char(sysdate,'YYYYMMDD');
:new.update_tm := to_char(sysdate,'HH24MISS');
END;
/

db2中怎么写?