使用<= 2的条件显示空计数
使用<= 2的条件显示空计数
提问于 2015-04-29 00:34:59
目前正在努力寻找诊断出的疾病，这些疾病已经被诊断了0到2次。我能够显示每种疾病被诊断了多少次，包括0，但一旦我试图查看计数为0-2的疾病，我的查询就不起作用了。
这将获得计数(包括0)：
select disease.name, count(diagnosed.diseaseid) as timesdiagnosed
from disease
left join diagnosed on disease.diseaseid = diagnosed.diseaseid
group by disease.name;这个代码不起作用：
select disease.name, count(diagnosed.diseaseid) as timesdiagnosed
from disease
left join diagnosed on disease.diseaseid = diagnosed.diseaseid
group by disease.name
order by disease.name
having count(diagnosed.diseaseid) <= 2;我的RDMBS是神谕。
回答 1
Stack Overflow用户
回答已采纳
发布于 2015-04-29 00:48:46
having子句应该放在order by之前和group by之后
select disease.name, count(diagnosed.diseaseid) as timesdiagnosed
from disease
left join diagnosed on disease.diseaseid = diagnosed.diseaseid
group by disease.name
having count(diagnosed.diseaseid) <= 2
order by disease.name页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/29932344
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