LINQ to SQL的LEFT OUTER JOIN - 過濾空結果

Question

我想複製下面的SQL到C＃LinqToSql

SELECT TOP(10) Keywords.* 
FROM   Keywords 
LEFT OUTER JOIN IgnoreWords 
    ON Keywords.WordID = IgnoreWords.ID 
WHERE (DomainID = 16673) 
    AND (IgnoreWords.Name IS NULL) 
ORDER BY [Score] DESC 

下面的C＃的LINQ給出了正確的答案。 （？做一個更好的方式）
但我不禁覺得我失去了一些東西

var query = (from keyword in context.Keywords 
    join ignore in context.IgnoreWords 
     on keyword.WordID equals ignore.ID into ignored 
    from i in ignored.DefaultIfEmpty() 
    where i == null 
    where keyword.DomainID == ID 
    orderby keyword.Score descending 
    select keyword).Take(10); 

產生的SQL看起來是這樣的：

SELECT TOP (10) 
     [t0].[DomainID] 
    , [t0].[WordID] 
    , [t0].[Score] 
    , [t0].[Count] 
    FROM [dbo].[Keywords] AS [t0] 
    LEFT OUTER JOIN 
    ( SELECT 1 AS [test] 
      , [t1].[ID] 
     FROM [dbo].[IgnoreWords] AS [t1] 
    ) AS [t2] 
    ON [t0].[WordID] = [t2].[ID] 
WHERE ([t0].[DomainID] = 16673) 
    AND ([t2].[test] IS NULL) 
ORDER BY [t0].[Score] DESC 

我怎樣才能擺脫這種多餘的內部選擇？ 它只是稍微昂貴，但每一位都有幫助！

Answer 1

我認爲你可以做這樣的事情，以消除左聯接，也許獲得更多的效率：

var query = (from keyword in context.Keywords 
      where keyword.DomainID == ID 
      && !(from i in context.IgnoreWords select i.ID).Contains(keyword.WordID) 
      orderby keyword.Score descending 
      select keyword) 
      .Take(10);