select min(a.fd_Id) as fd_Id,
a.fd_User,
a.fd_Effective
from mytable a
inner join (select fd_User,max(fd_Effective) as fd_Effective
from mytable
group by fd_User) b on a.fd_User=b.fd_User and
a.fd_Effective=b.fd_Effective
group by a.fd_User,a.fd_Effective