title: MySQL: Determine Table's Primary Key Dynamically
body: <p>I'm, generating a SQL query like this in PHP:</p>
  
  <pre><code>$sql = sprintf("UPDATE %s SET %s = %s WHERE %s = %s", ...);
  </code></pre>
  
  <p>Since almost every part of this query is dynamic I need a way to determine the table's primary key dynamically, so that I'd have a query like this:</p>
  
  <pre><code>$sql = sprintf("UPDATE %s SET %s=%s WHERE PRIMARY_KEY = %s", ...);
  </code></pre>
  
  <p>Is there a MySQL keyword for a table's primary key, or a way to get it?</p>
  
  <p>I've used the information_schema DB before to find information like this, but it'd be nice if I didn't have to resort to that.</p>