an outer join cannot be specified on a correlation column

select

(

   select nvl(sum(p.settle_pq),0)

          from pub_e_pq_amt p

           where

           p.prc_code != '00000000'

           and p.rcvbl_amt_id > 0

           and p.line_id=gl.line_id(+)

  ) as 用户用电量

from g_line