I have two tables: Students and Professors (both with usual info like name, last name, email... etc)
I also need to have info about their knowledge of foreign languages, and I guess that should be a third table (languages for example)
it should look like: Language_id, Language, Speaking, Writing, Listening,
Now, the tricky part for me is, how do I connect Language table with Students and Professors...
If I make another column foreign key Student_id.... that way I can connect with Students
but how do I also connect it with Professors table?
Do I also put foreign key Professor_id?
but what if I am inserting the data for some student, and his languages... and I insert student_id.... what of professor_id in the same row? can I leave it empty? Or is there someother way to accomplish it?