title: Confusing about <security-role> in web.xml
body: <p>I'm understand that 
  <code>&lt;security-role&gt;&lt;role-name&gt;Admin&lt;/role-name&gt;&lt;/security-role&gt;</code> 
  is for container map it with tomcat-users.xml  (realm)</p>
  
  <p>but I confuse about if I didn't use realm but I use database how container know which field in my database is for role-name or it have naming convention in database field name like "role_name" and container will know it </p>
  
  <p>Thank you for every advices</p>