如何使用 LINQ、NHibernate 和 uNHAddins 进行分组和排序

Question

我们正在构建一个 WPF 应用程序，使用 Oracle 数据库，还使用 ​​NHibernate 和 uNHAddins 扩展。在 DataGrid 中，我们尝试使用此查询 LINQ 从表中获取值：

return (from f in rFConsumption.GetAll()
                let d = f.CounterDtm
                where f.CounterDtm >= dataHoraInicio && f.CounterDtm <= dataHoraFim
                group f by (d.Year - 2000) * 384 + d.Month * 32 + d.Day into g
                select new RFConsumption
                {                       
                    COGCounter1 = (g.Sum(f => f.COGCounter1)),
                    BFCounter1 = (g.Sum(f => f.BFCounter1)),
                    NatGasCounter1 = (g.Sum(f => f.NatGasCounter1)),
                    MixGasCounter1 = (g.Sum(f => f.MixGasCounter1)),
                    COGCounter2 = (g.Sum(f => f.COGCounter2)),
                    BFCounter2 = (g.Sum(f => f.BFCounter2)),
                    NatGasCounter2 = (g.Sum(f => f.NatGasCounter2)),
                    MixGasCounter2 = (g.Sum(f => f.MixGasCounter2)),
                    COGCounter3 = (g.Sum(f => f.COGCounter3)),
                    BFCounter3 = (g.Sum(f => f.BFCounter3)),
                    NatGasCounter3 = (g.Sum(f => f.NatGasCounter3)),
                    MixGasCounter3 = (g.Sum(f => f.MixGasCounter3)),
                }
                ).ToList<RFConsumption>();

所以，我的问题是：

如何使用 NHibernate 来使用 group by、order by；

如何使 group by 将日期数据字段返回到指定的组。

Answer 1

您可以通过多种方式使用 NHibernate 编写相同的查询，对我来说最有趣的一种确实是 NHibernate QueryOver<>。
因此，如果您的查询工作正常，那么此查询应该可以工作：

 return Session.QueryOver<rFConsumption>()
            .Where( fc => (fc.CounterDtm >= dataHoraInicio && fc.CounterDtm <= dataHoraFim))
            .SelectList(list => list
                .SelectGroup(f => ((f.CounterDtm.Year - 2000) * 384 + f.CounterDtm.Month * 32 + f.CounterDtm.Day)) //use group by
                .Select(exp =>
                    new RFConsumption()   //here you define the return data type based on your specified group
                    {
                        // exp[0] represents the data returned and grouped by the above statements, so here you can reform it to fit into the form of your new entity
                        // exp[0] here will be equivilant to g in your query
                    })
                    .OrderBy( ee => ee.COGCounter1 ) //order by any of the properties of RFConsumption
                    .ToList<RFConsumption>();

您应该首先添加实体 RFConclusion：

public calss RFConsumption
{
     public int COGCounter1  { get; set; }
     public int BFCounter { get; set; } 
     ....
}