try this:
proc sql;
create table mo.D_paid_01 as
select a.claimno , b.Flag_date_0 as paid_time format = yymmdd10.
from mo.c_wj group a
left join (select claimno, max(Flag_date_0) as Flag_date_0
from mo.c_yj
group by 1 ) b
on a.claimno=b.claimno;
quit;