title: Difference in performance of two SELECTs and a SELECT plus JOIN
body: <p>I searched through the web to find out how a JDBC call is transmitted to the data base management system. What I want to know is, whether a JDBC call produces network traffic in order to communicate with the DBMS, even if the data base is local? </p>
  
  <p>I need to argue why two separate SQL <code>SELECT</code> statements are more expensive than a single one with a <code>JOIN</code>.</p>