投影类型average（datediff）总是返回0.0

这很令人费解;生成的SQL非常好，并且在手动运行时会得到正确的结果。
但是，在转换过程中，'AverageTime'字段被设置为0.0而不是正确的结果。
我的查询：投影类型average（datediff）总是返回0.0

var query = Session.CreateCriteria<Employee>() 
       .Add(Expression.In("Department", departments.ToArray())) // departmentsContains(employee)) 
       .Add(Expression.Ge("TimeOut", startTime)) // TimeOut >= startTime 
       .Add(Expression.Le("TimeOut", endTime)) // TimeOut <= endTime 
       .SetProjection(Projections.Alias(Projections.GroupProperty("Department.Id"), "Id") 
        , Projections.Alias(Projections.Count("Id"), "EmpCount")  //total emps 
        , Projections.Avg( //average of.. 
         Projections.SqlProjection("datediff(ss, {alias}.TimeIn ,{alias}.TimeOut) as AverageTime", new[] { "AverageTime" }, new[] { NHibernateUtil.Double })  // waiting time 
        ) 
       ) 
       .SetResultTransformer(NHibernate.Transform.Transformers.AliasToBean<EmpsForStatistics>()) 
       .List<EmpsForStatistics>(); 


private class EmpsForStatistics 
     { 
      public int DepartmentId { get; set; } 
      public int EmpCount { get; set; } 
      public double AverageTime { get; set; } 
     }

生成的查询是正确的：

SELECT this_.Department_id as y0_, count(this_.Id) as y1_, avg(cast(datediff(ss, this_.TimeOut ,this_.TimeIn) as DOUBLE PRECISION)) as y2_ 
FROM nHibernate_test.dbo.[Employees] this_ 
    WHERE this_.Department_id in (4004, 4005, 4006) 
    and this_.TimeOut >= '06/07/2011 08:27:58' and this_.TimeOut <= '06/07/2011 11:27:58' 
    GROUP BY this_.Department_id;

附：明显衡量员工的平均时间仅仅是为了榜样。我真正的疑问是其他实体..

来源

2011-06-07 J. Ed

好吧，我总是愚蠢的。忘了在Avg投影中添加一个Alias() ... duhh

来源

2011-06-09 07:04:03

投影类型average（datediff）总是返回0.0

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