select 
    MEMBER_CODE as MEMBER
    ,EMAIL as EMAIL
    --,EMAIL regexp '*' as DOMAIN
    --,INSTR(EMAIL, '@') as POS_atmark
    --,INSTR(EMAIL, '.') as POS_dot
    ,substr(EMAIL, INSTR(EMAIL, '@')+1, INSTR(EMAIL, '.')-INSTR(EMAIL, '@')-1) as DOMAIN
from 
    MEMBER_MST
order by DOMAIN desc, MEMBER desc