I don't have a way to test this, but I had to do something similar with DOB matching on names between two tables recently, and used something like:
select h.f_name, h.m_initial, h.l_name,
case
when h.f_name = d.f_name
and h.m_initial = d.m_initial
and h.l_name = d.l_name then d.dr_num
else null end
as 'dr_num'
from hal h,
dr d