with tmp as (
    select
        member_code, checkup_date, weight,
        lead(weight, 1) over (partition by member_code order by checkup_date desc) p_weight,
        row_number() over (partition by member_code order by checkup_date desc) num
    from health_checkup
)
select
    checkup_date CK_DATE,
    t.member_code CODE,
    last_name || first_name NAME,
    round(weight - p_weight, 1) CHG_WT
from tmp t, member_mst m
where
    t.member_code = m.member_code
    and num = 1
    and abs(weight * 10 - p_weight * 10) >= 50
order by chg_wt desc, code desc