Saving multi select field to database

Hi everyone,

Can someone help with providing a way to save a multi select field to the database.

I have three tables - doctors, location, and a many-to-many to link them. A doctor can work at multiple locations, and a location can have multiple doctors.

I am trying to add a new doctor to the doctors table using a form, I have set up the server connect to the doctors table and I am using a multi select field to choose the locations which the doctor can work from.

I am having troubles trying to insert the multiple locations from the form to the doctors table or to the many-to-many table. What is the best way to do such an action?

Thanks,