Please can somebody help me with this query.
I have a table called Grades containing
ClassID (text),
StudentID (text),
ReportNumber (integer),
Points (Integer)
ClassID, StudentID and ReportNumber can be used as a compound key to
reference a particular Points value.
I am trying to write a query, grouped by ClassID, to return the percentage
of students in each class whose points for ReportNumber = 6 is more than
the points for ReportNumber = 5 (for the same classID).
The ReportNumbers can be hard coded for the moment. I might use parameters
later.
I'm looking for a result something like
ClassID PercentOfImprovedStudents
==== =================
Eng1 56.6
Math2 60.3
Geog2 34.6
etc
Ideally I'd also like the total number of students in each class and the
number who have improved their points. (This is necessary to give meaning to
the percentage.)
I've tried playing around with self joins but am not getting very far.
Any help would be gratefully received. Thanks
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