simplifying SQL

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От garry saddington
Тема simplifying SQL
Дата
Msg-id 1170921254.10217.23.camel@localhost
обсуждение исходный текст
Ответы Re: simplifying SQL
Список pgsql-general
I have this query which essentially returns records that exist in one
table (studentclass) and not another (effortandattainment) to check when
teachers have entered their student grades.

select
distinct(studentclass.studentclassid),classes.subject,studentclass.studentid as
classstudent,classes.teacher,students.studentid,students.firstname,students.surname 
from studentclass left join effortandattainment
on(effortandattainment.classid=studentclass.classid and
effortandattainment.studentid=studentclass.studentid),students,classes

where students.studentid=studentclass.studentid
and studentclass.classid=classes.classid
and studentclass.classid not in (
select studentclass.classid
from studentclass inner join effortandattainment
on(effortandattainment.classid=studentclass.classid and
effortandattainment.studentid=studentclass.studentid)
)

I was wondering whether a simpler method exists to do the same thing or
is this OK.
Regards
Garry


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