効率的/複数のサブクエリのコードをクリーンアップ

Question

私は大きなサブクエリを構築し、それをフィルタリングしてからsum（）する必要があります。私はそれを集計し、それらの集約を一緒に結合しましたが、これは3つの同一のセクション（サブクエリ）を持つクエリで私を残します。

これを達成するための効率的、プログラム的、またはきれいな方法がありますか？私は、きれいで効率的なものが大きく違うかもしれないと理解しています。

各結合の変更された部分を強調表示しました。

select 
total_times.student_id 
, total_times.section_id 
, present_times.total as present 
, relation_times.total as relation 
, total_times.total as total 
from (
    select 
    s.student_id 
    , sec.section_id 
    , sum(sec_times.time) as total 
    from students s 
    join section_student_aff secsaff on secsaff.student_id = s.student_id 
    join sections sec on sec.section_id = secsaff.section_id 
    join (
     select distinct 
     site.site_id 
     , cal.date 
     , sec.section_id 
     , (time.end_time - time.start_time) as time 
     from calendar_days cal 
     join terms t on cal.date between t.start_date and t.end_date 
     join sessions ses on ses.session_id = t.session_id 
     join timeblocks blk on blk.session_id = ses.session_id 
     join timeblock_times time on time.timeblock_id = blk.timeblock_id 
     join sites site on site.site_id = ses.site_id 
     join section_timeblock_aff sectaff on sectaff.timeblock_id = blk.timeblock_id 
     join sections sec on sec.section_id = sectaff.section_id 
     where ses.academic_year = 2016 
     and time.day_of_week = extract(dow from cal.date) 
     order by site_id, date, section_id 
     ) sec_times 
     on sec_times.section_id = sec.section_id 

    --- Part 1 (no filter) --- 

    group by s.student_id, sec.section_id 
    ) total_times 
join (
    select 
    s.student_id 
    , sec.section_id 
    , sum(sec_times.time) as total 
    from students s 
    join section_student_aff secsaff on secsaff.student_id = s.student_id 
    join sections sec on sec.section_id = secsaff.section_id 
    join (
     select distinct 
     site.site_id 
     , cal.date 
     , sec.section_id 
     , (time.end_time - time.start_time) as time 
     from calendar_days cal 
     join terms t on cal.date between t.start_date and t.end_date 
     join sessions ses on ses.session_id = t.session_id 
     join timeblocks blk on blk.session_id = ses.session_id 
     join timeblock_times time on time.timeblock_id = blk.timeblock_id 
     join sites site on site.site_id = ses.site_id 
     join section_timeblock_aff sectaff on sectaff.timeblock_id = blk.timeblock_id 
     join sections sec on sec.section_id = sectaff.section_id 
     where ses.academic_year = 2016 
     and time.day_of_week = extract(dow from cal.date) 
     order by site_id, date, section_id 
     ) sec_times 
     on sec_times.section_id = sec.section_id 

    --- Part 2 --- 
    where exists (
     select null 
     from student_attendance sa 
     join attendance_flags af on af.attendance_flag_id = sa.attendance_flag_id 
     where 
     af.is_present=true 
     and sa.date = sec_times.date 
     and sa.sa_student_id = s.student_id 
     ) 
    -------------- 

    group by s.student_id, sec.section_id 
    ) present_times 
    on present_times.student_id = total_times.student_id 
    and present_times.section_id = total_times.section_id 
join (
    select 
    s.student_id 
    , sec.section_id 
    , sum(sec_times.time) as total 
    from students s 
    join section_student_aff secsaff on secsaff.student_id = s.student_id 
    join sections sec on sec.section_id = secsaff.section_id 
    join (
     select distinct 
     site.site_id 
     , cal.date 
     , sec.section_id 
     , (time.end_time - time.start_time) as time 
     from calendar_days cal 
     join terms t on cal.date between t.start_date and t.end_date 
     join sessions ses on ses.session_id = t.session_id 
     join timeblocks blk on blk.session_id = ses.session_id 
     join timeblock_times time on time.timeblock_id = blk.timeblock_id 
     join sites site on site.site_id = ses.site_id 
     join section_timeblock_aff sectaff on sectaff.timeblock_id = blk.timeblock_id 
     join sections sec on sec.section_id = sectaff.section_id 
     where ses.academic_year = 2016 
     and time.day_of_week = extract(dow from cal.date) 
     order by site_id, date, section_id 
     ) sec_times 
     on sec_times.section_id = sec.section_id 

    --- Part 3 --- 
    where sec_times.date between secsaff.entry_date and secsaff.leave_date 
    -------------- 

    group by s.student_id, sec.section_id 
    ) relation_times 
    on relation_times.student_id = total_times.student_id 
    and relation_times.section_id = total_times.section_id 
order by student_id, section_id 

Answer 1

WITHを使用して

、および条件付き合計が、それははるかに管理（そしておそらく速く）なり：完全

with 
    sec_times as (
    select distinct 
    site.site_id 
    , cal.date 
    , sec.section_id 
    , (time.end_time - time.start_time) as time 
    from calendar_days cal 
    join terms t on cal.date between t.start_date and t.end_date 
    join sessions ses on ses.session_id = t.session_id 
    join timeblocks blk on blk.session_id = ses.session_id 
    join timeblock_times time on time.timeblock_id = blk.timeblock_id 
    join sites site on site.site_id = ses.site_id 
    join section_timeblock_aff sectaff on sectaff.timeblock_id = blk.timeblock_id 
    join sections sec on sec.section_id = sectaff.section_id 
    where ses.academic_year = 2016 
    and time.day_of_week = extract(dow from cal.date) 
    ), 
    sec_times_full as (
    select 
    s.student_id 
    , sec.section_id 
    , sec_times.time 
    , exists (
     select null 
     from student_attendance sa 
     join attendance_flags af on af.attendance_flag_id = sa.attendance_flag_id 
     where 
     af.is_present=true 
     and sa.date = sec_times.date 
     and sa.sa_student_id = s.student_id 
     ) as is_present 
    , sec_times.date between secsaff.entry_date and secsaff.leave_date as is_relation 
    from students s 
    join section_student_aff secsaff on secsaff.student_id = s.student_id 
    join sections sec on sec.section_id = secsaff.section_id 
    join sec_times on sec_times.section_id = sec.section_id 
    ) 
select 
    student_id 
    , section_id 
    , sum(CASE WHEN is_present THEN time END) as present 
    , sum(CASE WHEN is_relation THEN time END) as relation 
    , sum(time) as total 
from sec_times_full 
group by student_id, section_id 
order by 1, 2