外层查询的表别名是 subquery ，需要把a和b改成 subquery 

SELECT

  subquery.organname,

  subquery.commname,

  subquery.incidentdealstatename,

  subquery.incidentnum,

  subquery.coordinatenum,

  subquery.incidentcontent,

  subquery.classname,

  subquery.deallimit,

  subquery.roomid,

  subquery.roomname,

  subquery.incidentman,

  subquery.admiman,

  subquery.admidate,

  subquery.reservedate,

  subquery.dispdate,

  subquery.dispman,

  subquery.receivingdate,

  subquery.arrivedata,

  subquery.finishdate,

  subquery.finishuser,

  subquery.finishusermobiletel,

  subquery.ratedworkhournumber,

  subquery.kpiratio,

  subquery.dealresult,

  subquery.dueamount,

  subquery.deviceid,

  subquery.closetime,

  subquery.closeuser,

  subquery.closesituation,

  subquery.isclose,

  subquery.nonormalclosereasons,

  subquery.replycontent,

  subquery.replyresult,

  subquery.servicequality,

  subquery.replydate,

  subquery.replyman,

  subquery.deletedate,

  subquery.deleteman,

  subquery.deletereasons,

  subquery.forwardreasons,

  subquery.forwarddatetime,

  subquery.dealman

FROM (

  SELECT

    a.organname,

    a.commname,

    a.incidentdealstatename,

    a.incidentnum,

    a.coordinatenum,

    a.incidentcontent,

    a.classname,

    a.deallimit,

    a.roomid,

    a.roomname,

    a.incidentman,

    a.admiman,

    a.admidate,

    a.reservedate,

    a.dispdate,

    a.dispman,

    a.receivingdate,

    a.arrivedata,

    a.finishdate,

    a.finishuser,

    a.finishusermobiletel,

    a.ratedworkhournumber,

    a.kpiratio,

    a.dealresult,

    a.dueamount,

    a.deviceid,

    a.closetime,

    a.closeuser,

    a.closesituation,

    a.isclose,

    a.nonormalclosereasons,

    a.replycontent,

    a.replyresult,

    a.servicequality,

    a.replydate,

    a.replyman,

    a.deletedate,

    a.deleteman,

    a.deletereasons,

    b.forwardreasons,

    b.forwarddatetime,

    a.dealman,

    ROW_NUMBER() OVER (PARTITION BY a.incidentnum ORDER BY b.forwarddatetime DESC) AS rn

  FROM (

    SELECT

      i.organname,

      i.commname,

      i.incidentdealstatename,

      i.incidentnum,

      i.coordinatenum,

      i.incidentcontent,

      i.classname,

      i.deallimit,

      i.roomid,

      i.roomname,

      i.incidentman,

      i.admiman,

      i.admidate,

      i.reservedate,

      i.dispdate,

      i.dispman,

      i.receivingdate,

      i.arrivedata,

      i.finishdate,

      i.finishuser,

      i.finishusermobiletel,

      i.ratedworkhournumber,

      i.kpiratio,

      i.dealresult,

      i.dueamount,

      i.deviceid,

      i.closetime,

      i.closeuser,

      i.closesituation,

      i.isclose,

      i.nonormalclosereasons,

      i.replycontent,

      i.replyresult,

      i.servicequality,

      i.replydate,

      i.replyman,

      i.deletedate,

      i.deleteman,

      i.deletereasons,

      i.incidentid -- 添加incidentid用于连接子查询

    FROM PMS_Base.dbo.view_HSPR_IncidentNewJH_Search_Filter AS i

    WHERE a.organname in ('${区域}')

and a.commname in ('${项目}')

  ) AS a

  LEFT JOIN PMS_Base.dbo.Tb_HSPR_IncidentForward AS b ON a.incidentid = b.incidentid AND a.rn_inner = 1

) AS subquery

WHERE subquery.rn <= 2