How to link one table cell to rows in another table?

Question

MySQL

Good evening experts! The problem is this. There is an activity table (production, sales, services, etc.) and a company table in which one column is the field of activity. One company can have several fields of activity. I can't figure out how to write keys from several rows of another table into one column? And then how do you make a selection? I will be grateful!

Answer 1

Make a link table. company_id field of activity_id