在group by子句postgresql中将null值返回为’0′
发布时间:2020-12-13 16:04:42 所属栏目:百科 来源:网络整理
导读:我使用count和group by来了解每天有多少订阅者购买: select count(s.email) from subscriptions s,orders o where o.subcription_id=s.id group by s.created_at 结果: created_at count------------------04-04-2011 106-04-2011 207-04-2011 110-04-2011
我使用count和group by来了解每天有多少订阅者购买:
select count(s.email) from subscriptions s,orders o where o.subcription_id=s.id group by s.created_at 结果: created_at count ------------------ 04-04-2011 1 06-04-2011 2 07-04-2011 1 10-04-2011 5 11-04-2011 9 但是我仍然希望空行返回为’0′.我该怎么做呢?请注意,我必须使用这两个表. created_at count ------------------ 04-04-2011 1 05-04-2011 0 06-04-2011 2 07-04-2011 1 08-04-2011 0 09-04-2011 0 10-04-2011 5 11-04-2011 9 解决方法SELECT s.created_at,COUNT(o.subsription_id) FROM subscriptions s LEFT JOIN orders o ON o.subcription_id = s.id GROUP BY s.created_at (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |