如果group by不返回任何值,则显示零 [英] show a zero if group by returns no value
本文介绍了如果group by不返回任何值,则显示零的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在尝试获取过去7天注册的用户数量以显示在图表上,如果mysql返回0而不是没有行,那将是很好的.目前,它每天只返回一行具有值的行
I am trying to get the amount of users signed up in the past 7 days to display on a chart and it would be nice if mysql returned 0 instead of no row. Currently it just returns a row for each day THAT has a value
SELECT date(created_at),
count(id)
FROM user_accts
WHERE date(created_at) < NOW()
AND date(created_at) > DATE_SUB(NOW(), INTERVAL 7 DAY)
GROUP BY date(created_at);
推荐答案
尝试:
SELECT DATE_SUB(CURDATE(), INTERVAL i DAY) date_created_at,
count(id)
FROM (SELECT 1 i UNION ALL
SELECT 2 UNION ALL
SELECT 3 UNION ALL
SELECT 4 UNION ALL
SELECT 5 UNION ALL
SELECT 6 UNION ALL
SELECT 7) i
LEFT JOIN user_accts ON date(created_at) = DATE_SUB(CURDATE(), INTERVAL i DAY)
/*AND owner_id = '131'*/
GROUP BY DATE_SUB(CURDATE(), INTERVAL i DAY)
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