轉換右外連接的Linq查詢在EF

Question

我想下面的SQL查詢轉換爲LINQ查詢，但我困惑：

SELECT * 
FROM dbo.Vahed 
INNER JOIN dbo.VahedMahsol ON dbo.Vahed.VahedId = dbo.VahedMahsol.VahedId 
RIGHT OUTER JOIN dbo.Mahsol ON dbo.VahedMahsol.MahsolId = dbo.Mahsol.MahsolId 

我寫了這個代碼：

vaheds = 
(
    from i in db.spGetVahedByWhatWhere(what, wherestr, int.Parse(whattype), new Guid(shahrid)) 
    join gr in db.GorohSenfis on i.GorohSenfiId equals gr.GorohSenfiID 
    join ct in db.Contacts on i.VahedId equals ct.VahedId 
    join vm in db.VahedMahsols on i.VahedId equals vm.VahedId 
    select i 
) 
.ToList(); 

，但我不知道如何轉換

RIGHT OUTER JOIN dbo.Mahsol ON dbo.VahedMahsol.MahsolId = dbo.Mahsol.MahsolId 

linq查詢。

Answer 1

，首先你可以重寫你的SQL查詢使用LEFT OUTER JOIN代替RIGHT OUTER JOIN（因爲這是比較容易轉換爲LINQ）：

SELECT * 
FROM dbo.Mahsol 
LEFT OUTER JOIN dbo.VahedMahsol ON dbo.Mahsol.MahsolId = dbo.VahedMahsol.MahsolId 
INNER JOIN dbo.Vahed ON dbo.VahedMahsol.VahedId = dbo.Vahed.VahedId 

現在可以將查詢轉換以上在LINQ這樣的：

vaheds = (
    from m in db.Mahsols 
    join vm1 in db.VahedMahsols on m.MahsolId equals v.MahsolId into vmgroup 
    from vm in vmgroup.DefaultIfEmpty() 
    join i in db.spGetVahedByWhatWhere(what, wherestr, int.Parse(whattype), new Guid(shahrid)) 
    on vm.VahedId equals i.VahedId 
    join gr in db.GorohSenfis on i.GorohSenfiId equals gr.GorohSenfiID 
    join ct in db.Contacts on i.VahedId equals ct.VahedId 
    select i 
).ToList(); 

我沒有辦法測試這個，但我希望它的工作原理。