NHibernate在child中按parentId分组,并从父表中获取此parentId的值

我在Header和Detail之间有一对多,如下类所示

public class Header
{
    public virtual string ScriptNumber { get; set; }
    public virtual IList<Detail> Details { get; set; }
    public virtual string StartTime { get; set; }
}

public class Detail
{
    public virtual string ScriptNumber { get; set; }
    public virtual DateTime UpdatedDate { get; set; }
    public virtual Header ProgramHeader { get; set; }   
}

我正在尝试查询Detail以按ScriptNumber分组,并从Header表中获取相应的StartTime。谁能帮我怎么做吗。 目前我的NHibernate查询是:

var changesInDetail = _session.QueryOver<Detail>()
                        .Where(x => x.UpdatedDate.IsBetween(changedFrom).And(changedTo))
                        .SelectList(list => list.SelectGroup(pr => pr.ScriptNumber))
                        .Future<string>();

How to get the StartTime from Header for the grouped by value in Detail?

        var changedScriptsInDetail1 = _session.QueryOver<Detail>(() => detailAlias)
                .JoinQueryOver(d => d.ProgramHeader, () => headerAlias)
                .Where(() => detailAlias.UpdatedDate.IsBetween(changedFrom).And(changedTo))
                .SelectList(list => list
                    .SelectGroup(pr => pr.ScriptNumber)
                    .SelectGroup(()=>headerAlias.StartTime)
                 )
                 .List<object[]>();