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
    CK_DATE,
    CODE,NAME,
    cast (we as real)/10 as  CHG_WT
    from (SELECT t2.CHECKUP_DATE CK_DATE
                    , t2.MEMBER_CODE CODE
                    , m.LAST_NAME || m.FIRST_NAME NAME
                    , CAST(t2.weight * 10 AS integer) - CAST(t3.weight * 10 AS integer)  as we
               FROM t2
                    INNER JOIN t3 ON t2.MEMBER_CODE = t3.MEMBER_CODE
                    JOIN MEMBER_MST m ON m.MEMBER_CODE = t2.MEMBER_CODE)
         where abs(we)>=50
order by 4 desc,2 desc;