1

LINQ to Entities にこのクエリがあります。

        var query = (from s in db.ForumStatsSet
                     where s.LogDate >= date1 && s.LogDate <= date2
                     group s by new { s.Topic.topicID, s.Topic.subject, s.Topic.Forum.forumName, s.Topic.datum, s.Topic.Forum.ForumGroup.name, s.Topic.Forum.forumID } into g
                     orderby g.Count() descending
                     select new TopicStatsData
                     {
                         TopicId = g.Key.topicID,
                         Count = g.Count(),
                         Subject = g.Key.subject,
                         ForumGroupName = g.Key.name,
                         ForumName = g.Key.forumName,
                         ForumId = g.Key.forumID
                     });

私はそれが一種の「悪」クエリであることを知っていますが、管理インターフェースでのみ使用されます。しかし、生成された SQL はまったく恐ろしいものです。この赤ちゃんを見てください。


exec sp_executesql N'SELECT TOP (50) 
[Project6].[C1] AS [C1], 
[Project6].[TopicId] AS [TopicId], 
[Project6].[C4] AS [C2], 
[Project6].[subject] AS [subject], 
[Project6].[name] AS [name], 
[Project6].[forumName] AS [forumName], 
[Project6].[C2] AS [C3]
FROM ( SELECT 
    [Project5].[TopicId] AS [TopicId], 
    [Project5].[subject] AS [subject], 
    [Project5].[forumName] AS [forumName], 
    [Project5].[name] AS [name], 
    1 AS [C1], 
     CAST( [Project5].[forumID] AS int) AS [C2], 
    [Project5].[C1] AS [C3], 
    [Project5].[C2] AS [C4]
    FROM ( SELECT 
        [Project4].[TopicId] AS [TopicId], 
        [Project4].[forumID] AS [forumID], 
        [Project4].[subject] AS [subject], 
        [Project4].[forumName] AS [forumName], 
        [Project4].[name] AS [name], 
        [Project4].[C1] AS [C1], 
        (SELECT 
            COUNT(cast(1 as bit)) AS [A1]
            FROM        [dbo].[tForumStats] AS [Extent14]
            LEFT OUTER JOIN [dbo].[tTopic] AS [Extent15] ON [Extent14].[TopicId] = [Extent15].[topicID]
            LEFT OUTER JOIN [dbo].[tForum] AS [Extent16] ON [Extent15].[forumID] = [Extent16].[forumID]
            LEFT OUTER JOIN [dbo].[tForum] AS [Extent17] ON [Extent15].[forumID] = [Extent17].[forumID]
            LEFT OUTER JOIN [dbo].[tForum] AS [Extent18] ON [Extent15].[forumID] = [Extent18].[forumID]
            LEFT OUTER JOIN [dbo].[tForumGroup] AS [Extent19] ON [Extent18].[forumGroupID] = [Extent19].[forumGroupID]
            LEFT OUTER JOIN [dbo].[tForum] AS [Extent20] ON [Extent15].[forumID] = [Extent20].[forumID]
            LEFT OUTER JOIN [dbo].[tForumGroup] AS [Extent21] ON [Extent20].[forumGroupID] = [Extent21].[forumGroupID]
            WHERE ([Extent14].[LogDate] >= @p__linq__25) AND ([Extent14].[LogDate] = @p__linq__25) AND ([Extent6].[LogDate] = @p__linq__25) AND ([Extent1].[LogDate]

I do not as anyone to explain that query but it would be great to get some tips on how to optimze the query so that it just do a simple regular join. Something like this works as fine if I write the SQL myself.

SELECT COUNT(*) AS NumberOfViews, s.topicid AS topicId, t.subject AS TopicSubject, g.[name] AS ForumGroupName, f.forumName AS ForumName 
FROM tForumStats s
join tTopic t on s.topicid = t.topicid
join tForum f on f.forumid = t.forumid
JOIN tForumGroup g ON f.forumGroupID = g.forumGroupID
WHERE s.[LogDate] between @date1 AND @date2
group by s.topicid,  t.subject, f.Forumname, t.Datum, g.[name]
order by count(*) desc

ところで、私はこのサイトが大好きです。デザインも使い勝手も抜群！うまくいくことを願っています:)

4

2 に答える 2

5

グループ内のすべてのテーブルを結合する代わりに、指定されたテーブルを自分で結合できます。これを試してみませんか。

from s in db.ForumStatsSet
join t in db.Topics on t.TopicId == s.TopicId
join f in db.Forums on f.ForumId == t.ForumId
join fg in db.ForumGroups on fg.ForumGroupId == f.ForumGroupId
where s.LogDate >= date1 && s.LogDate <= 
group s by new { t.TopicId, t.subject, f.forumName, t.datum, fg.name, f.forumID } into g
orderby g.Count() descending
select new TopicStatsData
{
 TopicId = g.Key.topicID,
 Count = g.Count(),
 Subject = g.Key.subject,
 ForumGroupName = g.Key.name,
 ForumName = g.Key.forumName,
 ForumId = g.Key.forumID
 });

ps: いくつかのエラーがあるかもしれませんが、論理的には正しいはずです!

于 2008-11-25T13:24:33.127 に答える
0

問題はグループ化構造にあると思います。最初にデータを抽出して (プロパティを経由する必要がないため)、抽出したデータでグループ化してみてください。

IOW、SQL のように LINQ を書いてみてください。

于 2008-11-25T13:23:30.227 に答える