帮忙优化一下sql语句

[江南野鹤]

SELECT N.ID
    ,N.Title
    ,N.CreateTime AS [Date]
    ,N.SecondCategoryID AS SC
    ,S.ClassName AS SN
    ,S.ParentID AS FC
    ,F.ClassName AS FN
FROM News N
    Left JOIN PE_Class S ON N.SecondCategoryID = S.ClassId
    Left JOIN PE_Class F ON S.ParentID = F.ClassID
WHERE N.ID IN
    (SELECT TOP 10 ID
        FROM News
        WHERE SecondCategoryId= N.SecondCategoryID
        ORDER BY CreateTime DESC)
    AND ChannelID = 1
ORDER BY fn,sn DESC

[tiandengyong]

SELECT top 10 N.ID
,N.Title
,N.CreateTime AS [Date]
,N.SecondCategoryID AS SC
,S.ClassName AS SN
,S.ParentID AS FC
,F.ClassName AS FN
FROM News N
Left JOIN PE_Class S ON N.SecondCategoryID = S.ClassId
Left JOIN PE_Class F ON S.ParentID = F.ClassID
WHERE ChannelID = 1
ORDER BY fn,sn DESC

[昵称被占用了]

数据量？索引情况？


比如：
news(SecondCategoryID,CreateTime)有无索引？

[utpcb]

用 exists 最好按照 CreateTime 建立降序的索引一个

[江南野鹤]

没有索引，数据量目前有1000左右

[江南野鹤]

你这个只能出10条记录，我要求每个SecondCategoryId出10个啊