如何在Entity框架中创建多个Left Join [英] How to create multiple Left Join in Entity framework
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问题描述
我有sql查询:
FROM tbl_UploadFile AS AllFiles
LEFT JOIN tbl_FirstFile AS firstFiles ON AllFiles.Guid=firstFiles.[FileId]
LEFT JOIN tbl_SecondFile AS secondFiles ON AllFiles.Guid=secondFiles.[FileId]
LEFT JOIN tbl_ThirdFile AS thirdFiles ON AllFiles.Guid=thirdFiles.[FileId]
WHERE firstFiles.[FileId] is NULL AND secondFiles.[FileId] is NULL AND thirdFiles.[FileId] is NULL;
此查询从tbl_UploadFile返回guid,如果此guid不在tbl_FirstFile,tbl_SecondFile和tbl_ThirdFile上使用。
它是工作正常。
This query return guid from tbl_UploadFile, if this guid doen't use on tbl_FirstFile, tbl_SecondFile and tbl_ThirdFile. It is work fine.
我尝试写Entity框架(使用GroupJoin),但我可以使GroupJoin仅为tbl_FirstFile:
I try to write on Entity Framework (using GroupJoin), but I can make GroupJoin only for tbl_FirstFile:
var unlinkedFiles = context
.Set<DbUploadFile>()
.GroupJoin(
context.Set<DbFirstFile>(),
file => file.Guid,
clFile => clFile.FileId,
(file, files) => new
{enter code here
FileGuid = file.Guid,
Children = files.Count()
})
.Where(x => x.Children == 0)
.ToList();
如何为所有表写多个GroupJoin?
How write multiples GroupJoin for all tables?
推荐答案
我不知道你的表名。但是你可以这样做:
I am not sure about your table names. But you could do something like this:
var result= (
from AllFiles in context.tbl_UploadFile
from firstFiles in context.tbl_FirstFile
.Where(w=>AllFiles.Guid=w.FileId).DefaultIfEmpty()
from secondFiles in context.tbl_SecondFile
.Where(w=>AllFiles.Guid=w.FileId).DefaultIfEmpty()
from thirdFiles in tbl_ThirdFile
.Where(w=>AllFiles.Guid=w.FileId).DefaultIfEmpty()
where firstFiles.FileId== null
where secondFiles.FileId == null
where thirdFiles.FileId == null
select AllFiles
).ToList();
然后做一个 GroupJoin
我认为
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