oracle的concat的用法

    select    concat(
          concat(
            concat(
              (
                select area_name
                from ec_area
                where
                  area_id = 11
              ), (
                select area_name
                from ec_area
                where
                  area_id = 109
              )
              ), (
                select area_name
                from ec_area
                where
                  area_id =1147
              )
          ), '北京****'
        ) as 用户地址
         from ec_area

select (select area_name  from ec_area where area_id = 11 ) ||
       (select area_name from ec_area where area_id = 109) ||
       (select area_name from  ec_area where area_id = 1147) ||( '北京****')
       as  用户地址
  from ec_area