帮忙优化一个Sql，在线等、急急急！！！

[NotFindObject]

表结构是 LetInLandPeople 人员信息表
DoorLog 操作记录表
DoorLimits 权限信息表
现在是要查询出每个人的权限有效期剩余天数，跟最后刷卡日期距离当前天数，这两个还要作为筛选条件
下面是原始SQL 正在努力优化中。。 奈何技术有限 求救！！！
select * from (

select ROW_NUMBER() over(order by ID) RowNumber,* from (

select
lp.Xm,lp.ID,lp.DeptID,tt.OprationTime,ValidTime,
DATEDIFF(DD,GETDATE(),ValidTime) ValidDays,
ISNULL(convert(varchar(10),DATEDIFF(DD,tt.OprationTime,GETDATE())),-1) SoltDays,
com.DeptName+' '+lp.Gzdw DZ,lp.Lxdh
from LetInLandPeople lp
left join(
select MAX(dl.OprationTime) OprationTime, Max(ValidTime) ValidTime,lp.ID from LetInLandPeople lp
join DoorLog dl on lp.ID=dl.PID
left join DoorLimits dls on dls.PID=lp.ID
where lp.Rzzt = 1
group by lp.ID) tt on tt.ID=lp.ID
join ComDepartment com on com.ID=lp.DeptID
where lp.Rzzt = 1
and DeptID in (select ID from dbo.GetDeptIDsByPID(2))

)aa
--where ValidDays between 7 and 30
--and SoltDays between 7 and 30
) cc
--where cc.RowNumber between 1 and 20

[NotFindObject]

感谢大神解我燃眉之急。。。在此祝大神仙福永享、寿与天齐！！！！！

[中国风]

在条件列加上索引，用以下语句测测 另外看执行计划，你的函数占用的资源百分比，占用高就贴出来看看能否优化

--select * from (

SELECT  ROW_NUMBER() OVER ( ORDER BY ID ) RowNumber ,
        *
FROM    ( SELECT    lp.Xm ,
                    lp.ID ,
                    lp.DeptID ,
                    tt1.OprationTime ,
                    tt2.ValidTime ,
                    DATEDIFF(DD, GETDATE(), tt2.ValidTime) ValidDays ,
                    ISNULL(CONVERT(VARCHAR(10), DATEDIFF(DD, tt1.OprationTime,
                                                         GETDATE())), -1) SoltDays ,
                    com.DeptName + ' ' + lp.Gzdw DZ ,
                    lp.Lxdh
          FROM      LetInLandPeople lp
                    CROSS APPLY ( SELECT    MAX(dl.OprationTime) OprationTime
                                  FROM      DoorLog dl
                                  WHERE     dl.PID = lp.ID
                                ) tt1
                    CROSS APPLY ( SELECT    MAX(ValidTime) ValidTime
                                  FROM      DoorLimits dls
                                  WHERE     dls.PID = lp.ID
                                ) tt2
                    JOIN ComDepartment com ON com.ID = lp.DeptID
          WHERE     lp.Rzzt = 1
                    AND DeptID IN ( SELECT  ID
                                    FROM    dbo.GetDeptIDsByPID(2) )
        ) aa;