如何显示SQL表中的所有记录并将这些记录与另一个表匹配？

I have set the PHP variable $accountnumber to be that of the user who is viewing their profile page. On the page, I have a block with the user's information populated from the database, and I have a list of all products that we have, and I want to put a check mark next to each one that the customer has by assigning a class to it. I have set the PHP variable $accountnumber to b