试试这个:
update talbename a set je = (select je from talbename b where b.zh = a.zh and to_char(b.rq,'yyyymmdd') = '20020630' and rownum < 2 ) where to_char(a.rq,'yyyymmdd') = '20020731';
update talbename a set je = (select je from talbename b where b.zh = a.zh and to_char(b.rq,'yyyymmdd') = '20020630' and rownum < 2 ) where to_char(a.rq,'yyyymmdd') = '20020731';
update talbename a set je = (select distinct b.je from talbename b where b.zh = a.zh and to_char(b.rq,'yyyymmdd') = '20020630')
where to_char(a.rq,'yyyymmdd') = '20020731';