newbie needs help with average calculation
sorry to annoy anyone with this question, but I do need help.
I have a school database for students reports. Each student has a unique ID number. In the reports table, the student has a new record for each subject they are doing (eg 1 record for Mathematics, 1 for Science etc, all with the common ID Number). For each subject the teacher allocates grades for different outcomes (eg 5 outcomes for Maths, such as A, A, B, D, C). I have a calculation that converts those grades to numbers (A = 5, B = 4 etc) and then averages those numbers and converts the average to an Overall Grade (eg a students' Overall Grade for Mathematics is a B).
End result is that a student doing 9 subjects has 9 Overall Grades.
What I need help with is averaging (or even summarising?) these Overall Grades for something like a GPA. Looking at other posts online here, I think the sticking point I have is that the data is all in the one table (and will remain that way!) and I need it based on the ID Number.
Please please please help!