我需要比较SQL中同一列中的两个日期

Question

/ *我需要比较事件编号相同的同一列中的2个日期。我已将日期从yyyymmdd hh：mm：ss转换为mm / dd / yyyy。我有以下数据我想比较：

event_date event_type   event_sub_type
2013/01/16  filed   
2013/01/10  pam            edue
2013/01/01  pam            edue
2013/04/01  filed   

当我运行以下查询时，我没有收到任何数据。* /

  SELECT 
   edue = (Select   MIN(CONVERT(VARCHAR(10),EVENT_DATE, 101)) 
        from tb_event e 
        where e.incident_id = vius_case.incident_id 
        and e.event_type = 'pam'
        and e.event_sub_type = 'edue'),   
  filedt = (Select MIN(CONVERT(VARCHAR(10),EVENT_DATE, 101))
        from tb_event f
        where f.incident_id = vius_case.incident_id 
        and f.event_type = 'filed' 
        and f.event_sub_type = 'ref'),   
 vius_asa.Name,   
 vius_event.event_information,   
 vius_case.incident_no  
 FROM vius_case 
    join  vius_event
     on  vius_case.incident_id = vius_event.incident_id
    join     vius_asa
     on vius_case.incident_id = vius_asa.incident_id   
    join  vius_incident_status 
     on  vius_case.incident_id = vius_incident_status.incident_id 
    join tb_event
     on   vius_case.incident_id = tb_event.incident_id

  WHERE  vius_case.case_type not like 'e%' 
    AND  vius_incident_status.case_status = 'O' 
    AND  tb_event.event_type = 'filed'  AND  
     (  exists (Select incident_no from vius_event d1,vius_event d2
      where d1.incident_id = vius_case.incident_id
       and  d2.incident_id = vius_case.incident_id
       and d1.event_type = 'filed' 
       and d2.event_type = 'pam' 
       and d2.event_sub_type = 'edue' 
      and d1.event_date >  d2.event_date))