Help with a running total (sort of)

[jdr5022]

Let me start by saying I am rather new to FileMaker. Ill try to give a general layout of my problem as best I can.

 

I work for a school and we are using FileMaker to generate bills based on which classes a student takes, how many credits that class is, and what that students parent company pays per credit. I have tables for Student and Class, and a join table Student_Class that houses which students are in which class.

 

Inside Student_Class i have a calculation field for each entry (Unique entries are determined by ClassID + StudentID) that holds the cost of that class for that particular student (a class can cost a different amount depending on the student). I also have a summary field that totals all these costs. That works perfectly.

 

My problem arises in that each student must pay a tech fee (however select students do NOT need to pay this fee). I added a TECH_FEE calculation field to my Student table, and it calculates each students technical fee. My problem is that I need to generate a total of these tech fees for the bill. I am uncertain how to accomplish this. I cant use a summary field in my Student_Class table because the values are help in the Student table.

 

I need to keep a running total of all the TECH_FEEs for each student appearing in the Student_Class table. Ive used MySQL before and I think this is going to require something equivilant to "GROUP BY USER_ID", but i couldnt even figure out how to add up all the tech fees. (would need to use group by to stop students from getting charged for each class, they only get charged once no matter how many classes they take).

 

Any help anyone can give would be appriciated, i can try to clarify the database more if needed also