oracle 批量修改 多个字段

update mydemontest t

set (a20121, b20121, c20121, d20121, e20121)

=

(selectpower_num,amount,get_amount,nopay_amount,power_price

from v2012_cost_monthpower p

where pay_year = '2012'and pay_month = '1'and t.ppt_code = p.ppt_code)