Okay, I see now
Thanks for the clarification!
Your data structure is ok, if you would provide this to smaller number of users, let’s say up to 100 or 1000, and I would not go more than that, for example if an user (student) has 50 subjects, that is already too much for me and my personal taste.
If you think long term, you can try structuring (if not late or to much work for you), by having three data types similar to what you have:
Data types:
Student (where list of students will be)
Subject (where list of subjects will be)
Teacher (where list of teacher, and maybe later teachers will be) [Let us know if you will have only one teacher throughout the time]
If a student will not have more than 20-30 subjects (per user), you can that add a list of subjects in the Student’s data type, otherwise I would already think to create a separate data type (4th here), naming it perhaps as “Taken_subjects”, where you will create a new data input each time user (student) adds a new subject to their profile, so you will have a separate (4th) data type where all the chosen subjects will be by the students, and from where you can easily delete and add new with a search, when each student (user) adds or removes a subject.
NOTE: This approach is not sustainable with new regulations in the Bubble and pricing model, where you will be charged by each workload unites, and in this case to search each time when user (Student) add the subject or want to delete, so you make the search in the backend, it would take to much of “workload unit”.
Not sure how long you are in the bubble, and maybe this is too much for you, bit advanced. If you are a beginner, and this app is just for a class. I think you don’t need to worry for a long term yet, and try to make it simple (small, and less complex for yourself) as possible.
If this is the case, I think you started on the right path:
You have three data types: List us teachers, subjects and students.
Each student has a field (list of subjects) where you can actually show a mark on a repeating group where all subjects are listed for user (student), if student has already data subject on their list or not, and if yes, you can showcase as checkbox “checked”, and if user want to remove, user “uncheck” the checkbox.
You can add the workflow triggered with “save button”, to change the list of user’s subjects, and in this case it would be easy for you, as you will have a “Current user” already there, and then if user contains this subject already to remove from the list, and if doesn’t then to add the subject.
How you got bit of a big picture here. Please let me know if you need still help, and perhaps if you can try to explain bit more about the app, so that I can make a shorter and more specific answer for you. Thanks!