how to save old value with new value in sql pro _ its urgent

how to save old value with new value in oracle or sql procedure

1. User Table 2. User_Hist Table

a> 1st table i have fileds like user Id , city

b> 2nd table ID, User Id, city ,city_old

------------------------------------------
user Id city

101 Andhra-Pradesh

------------------------------------------

2nd table i want like

-----------------------------------------------------------------
ID User Id City City_Old
-----------------------------------------------------------------
1 101 MP Andhra-Pradesh

1 101 UP MP

1 101 Kernataka UP

BUT IF I CHANGE CITY ON 2ND TIME SO I GOT THE RECORD ON TABLE LIKE

---------------------------------------------------------------------------
ID User Id City City_Old
--------------------------------------------------------------------------------
1 101 MP Andhra-Pradesh

1 101 MP Andhra-Pradesh

1 101 MP Andhra-Pradesh

and my procedure is

create or replace PROCEDURE PROC_UPDATE_CITY
(
P_CITY VARCHAR2,
P_USER_ID VARCHAR2,
P_RECORDS OUT NUMBER
)
AS

BEGIN

COMMIT;

P_RECORDS:= 0;

INSERT INTO USER_HIST(USER_ID,CITY)
select USER_ID,CITY from USER where USER_ID = P_USER_ID ;

UPDATE USER
SET CITY = P_CITY
WHERE USER_ID = P_USER_ID ;

UPDATE USER_HIST
SET CITY = P_CITY CITY_OLD = CITY where USER_ID = P_USER_ID ;

P_RECORDS:= 1;

END PROC_UPDATE_CITY;

SO HOW TO GET RECORD LIKE

-----------------------------------------------------------------
ID User Id City City_Old
-----------------------------------------------------------------
1 101 MP Andhra-Pradesh

1 101 UP MP

1 101 Kernataka UP

AND WHERE I DID MISTAKE