Linq左外連接和返回到許多記錄的聯合

Question

我正在轉換一個存儲過程，很好地工作到一個linq查詢，但沒有得到正確的記錄。 存儲過程如下所示：

SELECT isnull(a.CertificationId, cc.CertificationId) as CertificationId, 
    isnull(a.cipcode, cc.CipCode) as CipCode,isnull(a.Credential, lc.Credential) as Credential, 
    lc.LicensingCertificationProgram, lc.IssuingOrganization, isnull(a.ab, '') as ab 
FROM  enrCertificationCipCodes CC INNER JOIN 
    lkpCertifications lc ON CC.CertificationId = lc.CertificationId 
    left join 
     (SELECT pc.CertificationId, 
     cc.CipCode, 
     lc.Credential, 
     lc.LicensingCertificationProgram, 
     lc.IssuingOrganization, ab = 'Yes', 
     pc.psn 
      FROM  enrCertificationCipCodes CC INNER JOIN 
      lkpCertifications lc ON CC.CertificationId = lc.CertificationId 
      inner join (select * from enrProgramCertifications where PSN = @PSN) PC on cc.CertificationId = pc.CertificationId) as a on a.CertificationId = cc.CertificationId 
where cc.CipCode = @CipCode 
union 
select pc.CertificationId as CertificationId, p.cipcode as CipCode, other as Credential,'' as LicensingCertificationProgram, 
    '' as IssuingOrganization, 'Yes' as ab 
from (select * from enrProgramCertifications where CertificationId = '99999') pc join enrProgram p on pc.PSN = p.PSN 
    where p.CIPCode = @CipCode and p.PSN = @PSN 
    Union 
select '99999' as CertificationId, @CipCode as CipCode, 'Other' as Credential,'' as LicensingCertificationProgram, '' as IssuingOrganization, '' as ab 
order by ab desc, Credential 

LINQ查詢我已經是

var t = ((from a in LkpCertifications 
     join d in EnrProgramCertifications on a.CertificationId equals d.CertificationId into ad 
       from d in ad.DefaultIfEmpty() 
       join c in EnrCertificationCipCodes on a.CertificationId equals c.CertificationId 
       where c.CipCode == "52.1999" 
       select new { 
       CertificationId = a.CertificationId, 
       CipCode = c.CipCode, 
       Credential = a.Credential, 
       Licensing = a.LicensingCertificationProgram, 
       IssuingOrganization = a.IssuingOrganization, 
       Psn = d.PSN != null ? d.PSN : 0, 
       ab = d.PSN != null ? "Yes" : "" 
       }) 
       .Union (from k in EnrProgramCertifications 
       join l in LkpCertifications on k.CertificationId equals l.CertificationId where k.PSN == 19480 
       select new{ 
       CertificationId = k.CertificationId, 
       CipCode = "52.1999", 
       Credential = k.Other, 
       Licensing = l.LicensingCertificationProgram, 
       IssuingOrganization = l.IssuingOrganization, 
       Psn = k.PSN != null ? k.PSN : 0, 
       ab = k.PSN != null ? "Yes" : "" 
       })).ToList(); 

t.Dump(); 

的結果是，我正在從左邊的連接表多行。如果我試圖通過使用PSN編號限制左連接表中的行，那麼我不會從lkpCertifications表中獲得結果。 lkpCertifications持有所有認證，並且enrProgramCertifications僅保存那些已經被選擇的訂單和orderdetail設置的訂單。

所以我現在的成績看起來像

我應該只得到一個單一的項目54與0 PSN和一個55紀錄的19480.

的任何想法PSN問題？

Answer 1

我能夠通過使用幾個連接到defaultifempty（）來返回左外部連接的對象來解決此問題。

   certs = (from a in _context.LkpCertifications 
        join d in _context.EnrProgramCertifications on a.CertificationId equals d.CertificationId into ad 
        from d in ad.DefaultIfEmpty() 
        join c in _context.EnrCertificationCipCodes on a.CertificationId equals c.CertificationId into ac 
        from c in ac.DefaultIfEmpty() 
        where c.CipCode == CIP || d.Psn == Psn 
        select new vmManageCertifications 
         { 
         Psn = d.Psn == Psn ? d.Psn : 0, 
         Cipcode = c.CipCode == null ? "0" : c.CipCode, 
         CertificationId = a.CertificationId, 
         Credential = a.Credential == "Other" ? d.Other : a.Credential, 
         LicensingCertificationProgram = a.LicensingCertificationProgram, 
         IssuingOrganization = a.IssuingOrganization, 
         ProgramCertified = d.Psn == Psn ? true : false 
         }).ToList().GroupBy(i => i.CertificationId).Select(group => group.First()).OrderByDescending(i => i.ProgramCertified);