select a.teaid,a.teaname,count(*) studentcount
from teacher a,student b,teach_student c
where a.tesid=c.tesid and b.stuid=b.stuid
and a.teaage<40 and b.stuage>12;
from teacher a,student b,teach_student c
where a.tesid=c.tesid and b.stuid=b.stuid
and a.teaage<40 and b.stuage>12;
from teacher a,student b,teach_student c
where a.tesid(+)=c.tesid and b.stuid(+)=c.stuid
and a.teaage <40 and b.stuage >12;
from teacher a,student b,teach_student c
where a.tesid(+)=c.tesid and b.stuid(+)=c.stuid
and a.teaage <40 and b.stuage >12
group by a.tead,a.teaname;
where a.stuid=c.stuid and a.tesid=b.tesid and b.teaage<40 and c.stuage>12
group by b.teadid,b.teaname