title: Performance of inner join compared to cross join
body: <p>The effect of issuing an inner join is the same as stating a cross join with the join condition in the WHERE-clause. I noticed that many people in my company use cross joins, where I would use inner joins. I didn't notice any significant performance gain after changing some of these queries and was wondering if it was just a coincidence or if the DBMS optimizes such issues transparently (MySql in our case). And here a concrete example for discussion:</p>
  
  <pre><code>SELECT User.*
  FROM User, Address
  WHERE User.addressId = Address.id;
  
  SELECT User.*
  FROM User
  INNER JOIN Address ON (User.addressId = Address.id);
  </code></pre>