SQL connundrum. Can it be done?

I need to update a table with the output of a select statement like I listed below. The problem is that I expect my select to have about 7,000,000 rows returned so I want to update only one column in the table for all 7,000,000 rows. I was told you can't do it easily with SQL. I would either need PL/SQL or use SQL to generate 7,000,000 seperate update statements. Not efficient enough for me.
Sooooo... my challenge to you is, can I accomplish my multi-row update with standard old SQL statements? Thanks. To complicate matters one of my tables in the join is actually a select statement inline view.

update xyz_table x
set x.id3 =
  (select t.id3
   from xyz_table x,

       (select distinct id1, id2 from xyz_tmp_table where criteria_id='9998') t    where x.criteria_id ='9999' and <--- This is my subselect where clause

   x.id1 = t.id1 and
   x.id2 = t.id2 and
   x.id3 is null)
where x.criteria_id = '9999' and  <--- This is my update where clause
      x.id1 = t.id1 and
      x.id2 = t.id2 and
      x.id3 is null;