title: MySQL where clause equals anything (SELECT * WHERE col = ANY_VALUE)
body: <p>I'd like to create a query in MySQL that has an optional value. When the value is specified the query is filtered by that value, when the value is not all rows are returned. Here's the idea:</p>
  
  <pre><code>public function doQuery($item = 'ANY_VALUE') {
    $query = "SELECT * FROM table WHERE item = ?";
    db-&gt;fetchAll($query,array($item))
    ...
  }
  
  doQuery(); // Returns everything
  doQuery($item='item1'); // Returns only rows where item = 'item1'
  </code></pre>
  
  <p>Is there an easy way to do this without creating two query strings depending on the value of $item?</p>