title: Most efficient way to get table row count
body: <p>I currently have a database with over 6 million rows and growing.  I currently do SELECT COUNT(id) FROM table; in order to display the number to my users, but the database is getting large and I have no need to store all of those rows except to be able to show the number.  Is there a way to select the auto_increment value to display so that I can clear out most of the rows in the database?  Using <code>LAST_INSERT_ID()</code> doesn't seem to work.</p>