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LINQ to SQL複数テーブル左外部結合

このクエリはSQLにあり、 Entity Framework を使用してLINQに実装したいのですが、複数のテーブルの左外部結合を適用するにはどうすればよいですか？

SELECT d.bookingid,
       d.labid,
       d.processid,
       p.prid,
       p.prno,
       d.DestinationBranchID,
       d.SendStatus
FROM   dc_tpatient_bookingd d
       LEFT OUTER JOIN dc_tpatient_bookingm m ON d.bookingid = m.bookingid
       LEFT OUTER JOIN dc_tpatient p ON p.prid = m.prid
       LEFT OUTER JOIN dc_tp_test t ON d.testid = t.testid
       LEFT OUTER JOIN dc_tp_groupm gm ON t.groupid = gm.groupid
       LEFT OUTER JOIN dc_tpanel pn ON m.panelid = pn.panelid
       LEFT OUTER JOIN dc_tp_organization og ON og.orgid = m.clientid
       LEFT OUTER JOIN dc_tp_ward w ON w.wardid = m.wardid
       LEFT OUTER JOIN dc_tp_branch tb ON tb.BranchID = m.BranchID
WHERE  d.processid = 6
       AND ( ( m.branchId = 1
               AND d.DestinationBranchID = 0 )
              OR ( d.DestinationBranchID = 1
                   AND d.sendstatus = 'R' ) )
       AND d.testid IN (SELECT testid
                        FROM   dc_tp_test
                        WHERE  subdepartmentid = 13)
       AND date_format(m.enteredon, '%Y/%m/%d') BETWEEN '2013/06/15' AND '2013/06/15'
GROUP  BY m.bookingid
ORDER  BY d.priority DESC,
       m.bookingid ASC
c#mysqlsqllinqentity-framework
43
Ehsan Sajjad

以下は、LINQを使用した左外部結合の実装方法です。 GroupJoin （join...into構文）：

from d in context.dc_tpatient_bookingd
join bookingm in context.dc_tpatient_bookingm
     on d.bookingid equals bookingm.bookingid into bookingmGroup
from m in bookingmGroup.DefaultIfEmpty()
join patient in dc_tpatient
     on m.prid equals patient.prid into patientGroup
from p in patientGroup.DefaultIfEmpty()
// ... other joins here
where d.processid == 6 &&
      ((m.branchId == 1 && d.DestinationBranchID == 0) ||
       (d.DestinationBranchID == 1 && d.sendstatus == "R"))
// ... other conditions here
orderby d.priority descending, m.bookingid
select new {
   d.bookingid,
   d.labid,
   d.processid,
   p.prid,
   p.prno,
   m.bookingid // need for grouping
} into x
group x by x.bookingid into g
select g

このクエリは3つのテーブルを結合します。残りのテーブルも同じ方法で結合できます。

82
Sergey Berezovskiy