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wyj12501

wyj12501

V2EX member #171650, joined on 2016-05-04 12:41:14 +08:00
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薪资明确的招聘贴好评!
订单尾号 4642
select send_id, count(1)
from (select distinct send_id, receive_id from table)
group by send_id;

搜到一篇优化文章,可能有用
https://www.oschina.net/translate/use-subqueries-to-count-distinct-50x-faster
select *
from (select rownum rn, a.*
from (select * from XXX where YYY order by ZZZ) a
where rownum < 50)
where rn > 30;
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