Two primary non composite keys in a table
<p>I am working on a project and I realized I am unsure about how to use multiple primary keys. I have a table named "User_Details" that has the details of Customer ID, email address and password. From my understanding, I can use both Customer ID and email address as the primary key. In this case do I use only one as Primary Key or both? If I use both, do they become composite primary keys? </p>

<p>(PS. I have other tables, where the foreign key is the customer ID)</p>