I have tried this and get problems on the load, I am updating more than one field and my update looks like:
update (select a.account_no, b.bdom n, a.actg_cycle_dom o, b.actg_next_t p, a.actg_next_t q, b.actg_future_t r, a.actg_future_t s
from account_t a, account_stg b
where...