Question

我目前有这个linq声明：

from s in SubContentRevisions
where s.SubContentID.Equals("e3f319f1-65cc-4799-b84d-309941dbc1da")
&& s.RevisionNumber == (SubContentRevisions.Max(s1 => s1.RevisionNumber))
select s

生成此SQL（根据LINQPad）：

-- Region Parameters
DECLARE @p0 UniqueIdentifier = 'e3f319f1-65cc-4799-b84d-309941dbc1da'
-- EndRegion
SELECT [t0].[SubContentRevisionID], [t0].[SubContentID], [t0].[RevisionNumber], [t0].[RevisionText], [t0].[CreatedDate], [t0].[ModifiedDate]
FROM [SubContentRevision] AS [t0]
WHERE ([t0].[SubContentID] = @p0) AND ([t0].[RevisionNumber] = ((
    SELECT MAX([t1].[RevisionNumber])
    FROM [SubContentRevision] AS [t1]
    )))

如何让它生成此SQL语句？我似乎找不到任何相关的东西。（我需要它将where子句添加到子查询中）

-- Region Parameters
DECLARE @p0 UniqueIdentifier = 'e3f319f1-65cc-4799-b84d-309941dbc1da'
-- EndRegion
SELECT [t0].[SubContentRevisionID], [t0].[SubContentID], [t0].[RevisionNumber], [t0].[RevisionText], [t0].[CreatedDate], [t0].[ModifiedDate]
FROM [SubContentRevision] AS [t0]
WHERE ([t0].[SubContentID] = @p0) AND ([t0].[RevisionNumber] = ((
    SELECT MAX([t1].[RevisionNumber])
    FROM [SubContentRevision] AS [t1]
    WHERE [SubContentID] = @p0 -- **********Adds the where clause**********
    )))

Answer 1

我想你想要：

from s in SubContentRevisions
where s.SubContentID.Equals("e3f319f1-65cc-4799-b84d-309941dbc1da")
  && s.RevisionNumber == (SubContentRevisions.Where(s.SubContentID.Equals("..."))
                                             .Max(s1 => s1.RevisionNumber))
select s

或者，更清楚：

var specificSubContents = SubContentRevisions.Where(s => 
               s.SubContentID.Equals("e3f319f1-65cc-4799-b84d-309941dbc1da")

var query = from s in specificSubContents
            where s.RevisionNumber = s.Max(s1 => s1.RevisionNumber)
            select s;

或者，听起来你实际上可以做到：

var latest = (from s in SubContentRevisions
              where s.SubContentID.Equals("e3f319f1-65cc-4799-b84d-309941dbc1da")
              orderby s.RevisionNumber descending
              select s).FirstOrDefault();

Answer 2

如何将where子句添加到子查询（max）：

from s in SubContentRevisions
where s.SubContentID.Equals("e3f319f1-65cc-4799-b84d-309941dbc1da")
   && s.RevisionNumber == (SubContentRevisions
                                   .Where(s1 => s1.SubContentID.Equals(s.SubContentID))
                                   .Max(s1 => s1.RevisionNumber))
select s

LINQ MAX中的位置

2 个答案: