<application-policy name = "CNInfoStatReport">
       <authentication>
          <login-module code = "org.jboss.security.auth.spi.DatabaseServerLoginModule"
             flag = "required">
             <module-option name = "dsJndiName">java:jdbc/Postgres</module-option>
             <module-option name = "principalsQuery">
              select password from app_user where username=?
              </module-option>
             <module-option name = "rolesQuery">
              select role_name, 'Roles' from user_role where username=?
              </module-option>
            </login-module>
       </authentication>
    </application-policy>

<module-option name = "principalsQuery"></module-option>里怎么写？