select subjectname, classyear, div,dateon, count(*) as NoOfLecturesConducted
from lectures group by subjectname, classyear, div,dateon

select teacherid, subjectname, div,dateon,classyear,count(*) as
TotalStudents,count(case when attended = '1' then 1 else null end) as
AttendedStudents  from students group by teacherid, subjectname, div,dateon
,classyear