select * from class t where (select count(1) from class where name=t.name and age=t.age and sex=t.sex)>1
或者select a.* from class a join (select name,age,sex from class group by name,age,sex having count(1)>1)b on a.name=b.name and a.age=b.age and a.sex=b.sex
select * from class group by name,sex,age having count(*)>1
select name,age,sex from class group by name,age,sex having count(1)>1
group by后面的字段一定要在前面的列表项里面出现。 8楼正解
select id,count(*) ci from class group by(name,age,sex) order by ci desc
group by (name,age,sex);
from class t
where (select count(1) from class where name=t.name and age=t.age and sex=t.sex)>1
from class a
join (select name,age,sex from class group by name,age,sex having count(1)>1)b
on a.name=b.name and a.age=b.age and a.sex=b.sex
8楼正解