Listboxes are used to select data. Is there a way to do the opposite: to exclude anything selected from a listbox?
Let's say there's a table containing student IDs and names.
Student:
ID Name
1 John
2 Beth
3 Zack
There's another table that links each student to the classes they're taking.
Courses:
Student ID Course ID
1 Math101
1 Eng101
1 Art232
2 Math101
3 Chem101
3 Science283
3 Math101
Based on this example, John is taking three classes, Beth is taking one and Zack is taking three.
I wish to have listbox#1 for CourseID which would just show all the courses being taken by students.
The problem is I wish to have listbox#2 showing courseID, but exclude anything selected from listbox#2 from the current selection.
That means if I select Math 101 from listbox #1, my selection should include all 3 students.
But if I select Art232 and Chem101 from listbox#2, I want my current selection to exclude John and Zack.
This would help in finding this: "Show me students that are currently taking Math 101, who are not taking either one of Art232 or Chem 101."
I want the user to be able to first choose Math101, and also have the option to choose Art232 and Chem101 from a separate listbox so they can get excluded.
Is there a way to do this?
Perhaps even by using some expressions in charts so that it'll exclude students who are taking courses selected from the 'exclude' list?
Maybe by set analysis?
I find the challenge in the multi-link relationship between student and courses.
