如何验证用户对SQL表中特定行的访问权限？

I'm working on a project and I'm new to both web apps and SQL, so bear with me. I'm building an API and I want to make sure that my users only have access to certain rows in a specific table that have a foreign key to their customer id in another table, but have to be validated by user id in another table. (A single Customer has multiple Users and owns multiple Assets. For right now, all of the Customer's Users can access any Asset, but no Customers share an Asset or User.) The way I can think to do this is to do I'm working on a project and I'm new to both we