Nhibernate组成字符串投影

Question

我有这个mssql查询：

SELECT   CONVERT(VARCHAR,DATEPART( "YYYY"  ,A.Dispatch_DATE))
 + ' ' + CONVERT(VARCHAR,DATEPART( "MM"  ,A.Dispatch_DATE)) + ' ' 
 +       CONVERT(VARCHAR,DATEPART( "DD"  ,A.Dispatch_DATE)) + ' ' 
 +       CONVERT(VARCHAR,DATEPART( "HH"  ,A.Dispatch_DATE)) 
  AS DateNew,  A.System_Key AS IdNew FROM Archive A,ArchiveDest AD
   WHERE A.System_Key >= '201401240001'
  AND A.System_Key <= '20140124FFFF'
   AND (AD.System_Key = A.System_Key) 
   AND (AD.Dest_Key = '0001') 
AND (AD.XMode = 'R' OR AD.XMode = 'K' OR AD.XMode = 'H')

但是此查询也必须在Oracle数据库中运行。 我想在Nhibernate QueryOver对象中翻译此查询（我已使用Fluent构建了所有db映射对象）。 这是我翻译的错误信息：

 var hourResults = _session.QueryOver(() => a)
              .JoinAlias(() => a.ArchiveDest, () => ad)
              .Where(Restrictions.Ge(Projections.Property(() => a.SystemKey), "201401240001"))
              .And(Restrictions.Le(Projections.Property(() => a.SystemKey), "20140124FFFF"))
              .And(() => ad.ArchiveDestIdentifier.DestKey==  "0001")
              .And(new Conjunction().Add(() => ad.XMode == "R").Add( () =>  ad.XMode == "K" ).Add(() => ad.XMode == "H"))
              .Select(Projections.Property(() => a.DispatchDate.YearPart() + " " + a.DispatchDate.MonthPart() + " " + a.DispatchDate.DayPart()),Projections.Property(()=> a.SystemKey)).List<object[]>();

这只是一个子查询，但我的问题是： 如何转换：

SELECT   CONVERT(VARCHAR,DATEPART( "YYYY"  ,A.Dispatch_DATE))
 + ' ' + CONVERT(VARCHAR,DATEPART( "MM"  ,A.Dispatch_DATE)) + ' ' 
 +       CONVERT(VARCHAR,DATEPART( "DD"  ,A.Dispatch_DATE)) + ' ' 
 +       CONVERT(VARCHAR,DATEPART( "HH"  ,A.Dispatch_DATE)) 

到QueryOver选择投影？