with t1 as (
SELECT MEMBER_CODE,
       CHECKUP_DATE,
       weight
     , RANK() OVER (PARTITION BY member_code ORDER BY CHECKUP_DATE DESC) rnk
FROM HEALTH_CHECKUP ),
t2 as (select * from t1 where rnk=1),
    t3 as (select * from t1 where rnk=2)
select
    t2.CHECKUP_DATE CK_DATE
, t2.MEMBER_CODE CODE,
  m.LAST_NAME||m.FIRST_NAME NAME
,
    cast(cast(t2.weight*10 as integer)- cast(t3.weight*10 as integer) as real)/10 CHG_WT


    from t2 inner join t3 on t2.MEMBER_CODE = t3.MEMBER_CODE join MEMBER_MST m on  m.MEMBER_CODE=t2.MEMBER_CODE

order by 4 desc,2 desc;