title: Log4j JDBCAppender to log stacktraces
body: <p>Using <code>org.apache.log4j.jdbc.JDBCAppender</code>, how can I get stracktraces logged with <code>warn</code> and <code>error</code> into the <code>PatternLayout</code>.</p>
  
  <p>I'm logging like</p>
  
  <pre><code>logger.warn("warning description", e);
  logger.error("error description", e);
  </code></pre>
  
  <p>I get the String descriptions into the table, but the Throwable's stacktrace is now where.  Is there another parameter that I can access via the <code>PatternLayout</code>. Currently I am using</p>
  
  <pre><code>"INSERT INTO app_logs (app, log_date, log_level, location, loc, message) VALUES ('my-apps-name', '%d{ISO8601}','%p', '%C.java', '%C{1}.java:%L', '%m')" 
  </code></pre>
  
  <p>into a table</p>
  
  <pre><code>TABLE `app_logs` (
    `id` int(11) NOT NULL AUTO_INCREMENT,
    `app` varchar(255) DEFAULT NULL,
    `log_date` varchar(255) DEFAULT NULL,
    `log_level` varchar(255) DEFAULT NULL,
    `location` varchar(255) DEFAULT NULL,
    `loc` varchar(255) DEFAULT NULL,
    `message` text, 
    PRIMARY KEY (`id`)
  )
  </code></pre>