NOT EXISTS
is an excellent choice. Almost always better than NOT IN
. More details here.
I simplified your query a bit (which looks fine, generally):
SELECT DISTINCT ON (c.class_id, a.school_date)
c.class_id, c.class_name, c.grade_id
,g.linked_calendar, aa.calendar_id
,a.school_date, a.minutes
,t.staff_id, s.first_name, s.last_name
FROM school_classes c
JOIN teacher_join_classes_subjects t USING (class_id)
JOIN staff s USING (staff_id)
JOIN school_gradelevels g ON g.id = c.grade_id
JOIN attendance_calendars aa ON aa.title = g.linked_calendar
JOIN attendance_calendar a ON a.calendar_id = aa.calendar_id
WHERE t.syear = 2013
AND s.syear = 2013
AND aa.syear = 2013
AND t.does_attendance = 'Y' -- looks like it should be boolean!
AND t.subject_id IS NULL
AND a.school_date < CURRENT_DATE
AND NOT EXISTS (
SELECT 1
FROM attendance_completed x
WHERE x.class_id = c.class_id
AND x.school_date = a.school_date
AND (x.period_id = 101 AND a.minutes >= 151 OR -- actually numbers?
x.period_id = 95 AND a.minutes = 150)
)
ORDER BY c.class_id, a.school_date, ???
What seems to be missing is ORDER BY
which should accompany your DISTINCT ON
. Add more ORDER BY
items in place of ???
. If there are duplicates to pick from, you probably want to define which to pick.
Numeric literals don't need single quotes and boolean
values should be coded as such.
You may want to revisit the chapter about data types.