how to combine 2 cte to get grouping - mysql

Question

hi i need help combining 2 cte to get who get 100 attendance percentage but failed at exam
here my first cte
with main as(
select ca.STUDENT_ID,
ca.SCHEDULE_ID,
s.COURSE_ID,
co.NAME as course_name,
st.NAME,
count(ca.ID) as total_attendance,
((CHAR_LENGTH(s.COURSE_DAYS) - CHAR_LENGTH(REPLACE(s.COURSE_DAYS , ',', '')) + 1) * 13) as attendance_needed
from univ.course_attendance ca
left join univ.schedule s on ca.SCHEDULE_ID = s.ID
left join univ.student st on ca.SCHEDULE_ID = st.ID
left join univ.course co on ca.SCHEDULE_ID = co.ID
group by ca.STUDENT_ID, ca.SCHEDULE_ID
)
select *,total_attendance/attendance_needed as attendance_percentage
from main
order by 1,2;
second cte
;with inputdata as
(
select es.STUDENT_ID,es.EXAM_ID,es.SCORE,e.PASS_THRESHOLD, s.NAME , c.NAME as Course_name, es.EXAM_DT,
case
when SCORE>=PASS_THRESHOLD then 'PASS'
else 'Fail'
end as Flag
from exam_submission es
left join student s on es.STUDENT_ID = s.ID
left join exam e on es.EXAM_ID = e.ID
left join course c on e.COURSE_ID = c.ID
)
select * from inputdata I
join
( select student_id,exam_id from
inputdata
group by student_id, exam_id
)T on I.student_id=T.student_id and I.exam_id=T.exam_id
order by exam_dt asc
result:
what i need student name, course name, attendace percentage & flag "failed/pass"

Answer 1

Just chain multiple table expressions in a single CTE by introducing "aliases" like main_ordered for the first CTE and inputdata_grouped for the second one. I'm sticking with the original naming, but it could be improved.
with
main as (
select ca.STUDENT_ID,
...
group by ca.STUDENT_ID, ca.SCHEDULE_ID),
main_ordered as (
select *,total_attendance/attendance_needed as attendance_percentage
...
order by 1,2),
inputdata as (
select es.STUDENT_ID,es.EXAM_ID,es.S...
...),
inputdata_grouped as (
select * from inputdata I
...
group by student_id, exam_id...
...
order by exam_dt asc)
select *
from main_ordered join inputdata_grouped on ...