MySQL Generate order number function

DROP TABLE IF EXISTS ' order_seq ';
CREATE TABLE ' Order_seq ' (
' Timestr ' int (one) is not NULL,
' ORDER_SN ' int (one) not NULL
) Engine=innodb DEFAULT Charset=utf8;

DROP FUNCTION Order_seq;

Create function Order_seq ()
Returns integer
Begin
declare v_cnt integer;
declare v_timestr integer;
declare V_value integer;
DECLARE rowcount BIGINT;
Set V_timestr =date_format (now (), '%y%m%d ');
Select ROUND (RAND () *100,0) + 1 into v_cnt;
UPDATE order_seq Set order_sn = Order_sn + v_cnt where timestr = V_timestr;
If Row_count () = 0 Then
INSERT into ODER_SEQ values (V_TIMESTR,V_CNT);
End If;
Select CONCAT (V_timestr,lpad (order_sn,7,0)) into V_value from order_seq where timestr = V_timestr;
return v_value;
End

--Running results

SELECT Order_seq ();

MySQL Generate order number function