Many-to-many relations in RDBMS databases

Question

What is the best way of handling many-to-many relations in a RDBMS database like mySQL?

Have tried using a pivot table to keep track of the relationships, but it lea

Answer 1

I would use a pivot table, but I don't see where your issues are coming from. Using a simple student/class example:

Student
-------
Id (Primary Key)
FirstName
LastName

Course
------
Id (Primary Key)
Title

StudentCourse
-------------
StudentId (Foreign Key -> Student)
CourseId (Foreign Key -> Course)

Or, as somebody else mentioned in response to your Student/Teacher/Course question (which would have an additional table to store the type of person in the course):

PersonType
----------
Id (Primary Key)
Type

Person
------
Id (Primary Key)
FirstName
LastName
Type (Foreign Key -> PersonType)

Course
------
Id (Primary Key)
Title

PersonCourse
------------
PersonId (Foreign Key -> Person)
CourseId (Foreign Key -> Course)

The Student table contains student information, the Course table stores course information...and the pivot table simply contains the Ids of the relevant students and courses. That shouldn't lead to any null/empty columns or anything.