title: Can someone explain MySQL foreign keys
body: <p>I know what they are my question is, how do you link them or are they automatically linked when you have identical names in different tables. 
  Here is an example:</p>
  
  <p>Say I have an [orders] table and a [customer] table. 
  Each row in the [orders] table has a customer_id number which is associated with the customer_id in the [customer] table. 
  So how do I get the customer information by referencing the order? 
  What would be the sql query?</p>