Linq to Entity Left outer join

  1.此方法等同 SQL Left Outer Join 效果 EF V1(.FrameWork 3.5)所能使用的方法.
       Dim qbase = From sp In ctx.SysPhrase _
       Where (sp.Owner = DivCode Or sp.Owner = FormCode) _

       And sp.PhraseType = PhraseType And sp.Enabled = True _
       Let Value = (From sc In ctx.SysCodeDefinition _
                           Where sc.CodeName = "GroupType" And sc.CodeValue = sp.GroupType _
                           Select sc.CodeDescription, sc.CodeValue).FirstOrDefault _
 Select New With {.PhraseName = sp.PhraseName, sp.GroupType, sp.PhraseContent,sp.  ViewSeq,.CodeDescription = Value.CodeDescription}
        dt = LINQGet.LINQToDataTable(qbase)

 

 2.此方法等同 SQL Left Outer Join 效果 EF V4(.FrameWork 4.0)所能使用的方法,V4才支援DefaultIfEmpty.
      Dim qbase = From sp In ctx.SysPhrase _
      Group Join c In ctx.SysCodeDefinition On sp.GroupType Equals c.CodeValue _
      Into Code = Group _
      From cp In Code.DefaultIfEmpty _
 Where (sp.Owner = DivCode Or sp.Owner = FormCode) And sp.PhraseType = PhraseType And sp.Enabled = True And cp.CodeName = "GroupType" _
      Select New With {.PhraseName = sp.PhraseName, sp.GroupType, sp.PhraseContent, sp.ViewSeq, .CodeDescription = cp.CodeDescription}
       dt = LINQGet.LINQToDataTable(qbase)