select a.className as '班级名称',
b.zyName as '所属专业',
(select count(*) from Student c where a.classId=c.classId) as '人数'
from Class a
inner join ZY b on a.zyId=b.zyId
b.zyName as '所属专业',
(select count(*) from Student c where a.classId=c.classId) as '人数'
from Class a
inner join ZY b on a.zyId=b.zyId
解决方案 »
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b.zyName as '所属专业',
c.qty as '人数'
from Class a
inner join ZY b on a.zyId=b.zyId
inner join (select classId,count(*) as qty from Student group by classId) c on a.classId=c.classId
from Class c, ZY z, Student s
where s.classId = c.classId and c.zyId = z.zyId
或者select a.className as '班级名称',
b.zyName as '所属专业',
count(c.stuId) as '人数'
from Class a
inner join ZY b on a.zyId=b.zyId
left join Student c on a.classId=c.classId
group by a.className,b.zyName