update t1
set Source = 'SS'
, PP = t2.MaxPP
from Table1 t1
join (
select Email_address
, max(PP) as MaxPP -- Pick max PP from the available group
from Table2
where Source = 'SS'
group by
Email_address
) t2
on t2.Email_address = t1.Email_address
If there is more than one matching PP
value in Table2
, you have to a choice. The above example picks the maximum. If that's not what you're looking for, please clarify your question.