select * from pn_tablename a join pn_tablename b;odps不支持无 on 的 join 会报
ODPS-0130252 Cartesian product is not allowed without map join 的错误
可以往select里增加字段来绕过这个限制
select * from (select *, 1 as raoguo from pn_tablename) a join (select *,1 as raoguo from pn_tablename) b on a.raoguo = b.raoguo;
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