title: Error Message When Running MyBatis at the first time
body: <p>I have a strange problem when running my application in JBOSS at the first time:
  The error message is:</p>
  <pre><code>javax.servlet.ServletException: java.lang.IllegalArgumentException: Mapped Statements collection already contains value for project.services.dao.workerDAO.getAllWorkers
  org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:535)
      org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:433)
      org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
      org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
      org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
      javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
      javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
      org.displaytag.filter.ResponseOverrideFilter.doFilter(ResponseOverrideFilter.java:125)
      org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
  </code></pre>
  <p>Mapper File: project.services.dao.sql.workerDAO.xml</p>
  <pre><code>&lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot; ?&gt;
  &lt;!DOCTYPE mapper PUBLIC &quot;-//mybatis.org//DTD Mapper 3.0//EN&quot; &quot;http://mybatis.org/dtd/mybatis-3-mapper.dtd&quot; &gt;
  
  &lt;mapper namespace=&quot;project.services.dao.workerDAO&quot;&gt;
  
      &lt;select id=&quot;getAllWorkers&quot; parameterType=&quot;java.lang.String&quot;
          resultType=&quot;Worker&quot;&gt;
  
           Select wrk.Id As workerId, wrk.Nm As workerName
           From Worker wrk
  
      &lt;/select&gt;
  
  &lt;/mapper&gt;
  </code></pre>
  <p>However, for the second time, there is no Error Message.</p>