title: mysql_num_rows from multiple tables
body: <p>I'm looking to count the amount of fields in 5 tables and display a result. I currently do this for a single table</p>
  
  <pre><code>    $variable = mysql_num_rows(mysql_query("SELECT id FROM table1"));
  </code></pre>
  
  <p>What is the most efficient way to include and count all <code>id</code> from <code>table2</code>, <code>table3</code>, <code>table4</code> and <code>table5</code>?</p>
  
  <p>Thanks</p>