vb.net 在 linq 中使用左连接查询
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Query with left join in linq
提问by blop
Hello I 'm trying to do a query in linq but I think I need some help...
您好，我正在尝试在 linq 中进行查询，但我想我需要一些帮助...
I have two table: langAvailable and Translations I want a 'line' even if theres no translation recorded
我有两个表：langAvailable 和 Translations 我想要一个“行”，即使没有记录翻译
For instance:
例如：
LangId: 1 TranslationID:10 Translation: Hello
LangId: 2 TranslationID:10 Translation: Bonjour
LangId: 1 TranslationID:11 Translation: Thanks
LangId: 2 TranslationID:11 Translation:
Here's what I do:
这是我所做的：
Dim query = From c In db.LangAvailable _
Join o In db.Translate On c.ID_Lang Equals o.Lang_ID _
Where o.TranslationID = 243 _
Select New With {c.LangId, o.Translation}
This only give me one record if there s no translation in the translate table... Any idea how I can get that?
如果翻译表中没有翻译，这只会给我一个记录......知道我怎么能得到吗？
Thanx
谢谢
回答by HotN
You can use Group Join to do what you're trying to do. Try this:
您可以使用 Group Join 来做您想做的事情。尝试这个：
Dim query = From c In db.LangAvailable _
Group Join o In db.Translate On c.ID_Lang Equals o.Lang_ID Into Group _
From o In Group.DefaultIfEmpty() _
Where o.TranslationId = 243 _
Select LangId = c.ID_Lang, Translation = If(o.Translation Is Nothing, Nothing, o.Translation)
