case when

   <select   >
          <include ref>
          select T_LIMIT_FIELD.*,
             (
                  case state
                     when 'N' then '下线'
                     when 'Y' then '上线'                    
                      end               
             ) as stateStr          
           from T_LIMIT_FIELD  where IS_DELETE='N'
                <include ref>
          order by ADD_TIME desc
          <include ref/>
    </select>