如何實現一個左外連接的實體框架

Question

我有以下SQL查詢： -

select distinct * from dbo.Profiles profiles 
left join ProfileSettings pSet on pSet.ProfileKey = profiles.ProfileKey 
left join PlatformIdentities pId on pId.ProfileKey = profiles.Profilekey 

我需要將其轉換爲LinqToEntities表達。我試過以下內容： -

from profiles in _dbContext.ProfileSet 
          let leftOuter = (from pSet in _dbContext.ProfileSettingSet 
              select new 
                 { 
                  pSet.isInternal 
                 }).FirstOrDefault() 
select new 
             { 
              profiles.ProfileKey, 
              Internal = leftOuter.isInternal, 
              profiles.FirstName, 
              profiles.LastName, 
              profiles.EmailAddress, 
              profiles.DateCreated, 
              profiles.LastLoggedIn,            
             }; 

上面的查詢工作正常，因爲我沒有考慮第三個表「PlatformIdentities」。單一的左外連接與我上面所做的一樣。我如何包含PlatformIdentities（第三張表）？我基本上想要將我在本文開頭指定的SQL查詢（這正是我所需要的）轉換爲LinqToEntities。

感謝

Answer 1

讓我知道，如果你要選擇不同的東西，但真正加盟低於

from p in _dbContext.ProfileSet 
       join ps in _dbContext.ProfileSettings on p.ProfileKey = ps.ProfileKey into a 
       join pi in _dbContext.PlatformIdentities on p.ProfileKey = pi.ProfileKey into b 

       select new 
       { 
        profiles.ProfileKey, 
        profiles.FirstName, 
        profiles.LastName, 
        profiles.EmailAddress, 
        profiles.DateCreated, 
        profiles.LastLoggedIn, 
        PlatformSettings = a.Select(x=>x), 
        PlatformIdentities = b.Select(y=>y) 
       }