Question

Here is the problem I’m trying to solve:

Entity A : a_id
Entity B : b_id
One A can use Many B's. However, not all Bs are used by all As.

Here is the best example I can think of :

One teacher has many students.
Some students are taught by more than one teacher.

What is a relationship so I can add/remove students being taught by one teacher, but not affect the teachers already teaching said students?

Answer 1

you need a third table known as mapping between this two tables.create this table so:

Table Student_Teacher_Mapping

   Id (Int)
   TeacherId(Int)  // foreign key for teacher table  
   StudentId(Int)  // foreign key for student table

i think this is what you want.