NHibernate Fluent (QueryOver) 使用相关子查询替换 HQL

Question

背景，使用 FluentNHibernate，最新的开发版本与 NHibernate 3.0 一起使用。

以下是 WorkIncident 的类型声明：

// Enumeration used in class below.
public enum TicketStatus
{
    Open = 1,
    Closed = 10,
    Hold = 20
}

// Ticket class.
public class WorkIncident
{
    public virtual int EntryId { get; set; }
    public virtual int TicketNumber { get; set; }
    public virtual string ModifierNtId { get; set; }
    public virtual DateTime ModifiedDate { get; set; }
    public virtual TicketStatus Status { get; set; }
    public virtual int Version { get; set; }
    public virtual string Title { get; set; }
    public virtual string Details { get; set; }
}

// FluentNHibernate mapping
public class WorkIncidentMap : ClassMap<WorkIncident>
{
    public WorkIncidentMap()
    {
        Table("incident_details");
        Id( wi => wi.EntryId, "wiid");
        Map(wi => wi.TicketNumber, "workitem_number");
        Map(wi => wi.Title, "workitem_title");
        Map(wi => wi.Details, "workitem_comment");
        Map(wi => wi.ModifiedDate, "workitem_modified_on");
        Map(wi => wi.ModifierNtId, "modified_by_worker_nt_id");
        Map(wi => wi.Status, "workitem_status_lookup_id").CustomType<EnumType<Status>>();
        Map(wi => wi.Version, "workitem_version");
    }
}

映射工作正常，我可以毫无问题地执行如下查询：

session.QueryOver<AltirisIncident>()
    .Where(ai => ai.ModifierNtId == worker.Name.Replace("\\", @"\"))
    .AndRestrictionOn(ai => ai.ModifiedDate)
    .IsBetween(DateTime.Today)
    .And(DateTime.Today.AddDays(1))
    .List<WorkIncident>();

这为我提供了当前日期特定用户接触的所有工作项目（基本上是帮助台故障单）。

但是，我在将以下 HQL 翻译为流畅的声明时遇到了麻烦：

from    WorkIncident as t1
where   t1.ModifierNtId = :ntid
and     t1.ModifiedDate between :startdate and :enddate
and     t1.Status = :status
and     (t1.Version = 1
or      t1.TicketNumber in (
    select    t2.TicketNumber
    from      WorkIncident as t2
    where     t2.Status != t1.Status
    and       t2.TicketNumber = t1.TicketNumber
    and       t2.Version = t1.Version - 1))

此查询为我提供了由工作人员置于关闭状态的所有工作项的列表。考虑到工单在数据库中的存储方式（每张工单都有多个记录（每次更新一条），并且主管通常会在工作人员关闭工单后向工单添加注释，导致我无法只查看工单的情况具有关闭状态的最后一个版本号可以可靠地告诉我谁关闭了票证，

我们将不胜感激，因为我希望尽可能远离 HQL 和魔术字符串。

Answer 1

我认为这应该可以解决问题。困难的部分实际上是处理那里的数学运算。你必须进入 SQLFunction 投影

session.QueryOver<WorkIncident>(() => t1Alias)
                .Where(w => w.ModifierNtId == "test")
                .And(w => w.ModifiedDate < DateTime.Now && w.ModifiedDate > DateTime.Now)
                .And(w => w.Status == TicketStatus.Open)
                .And(Restrictions.Disjunction()
                    .Add(Restrictions.Where<WorkIncident>(w => w.TicketNumber == 1))
                    .Add(Subqueries.WhereProperty(() => t1Alias.TicketNumber).In(
                        QueryOver.Of<WorkIncident>(() => t2Alias)
                                .Where(() => t2Alias.Status != t1Alias.Status)
                                .And(() => t2Alias.TicketNumber == t1Alias.TicketNumber)
                                .And(Restrictions.EqProperty(
                                    Projections.Property<WorkIncident>(w=> w.Version), 
                                    Projections.SqlFunction(
                                        new VarArgsSQLFunction("(","-",")"),
                                        NHibernateUtil.Int32,
                                        Projections.Property(()=> t1Alias.Version),
                                        Projections.Constant(1)
                                    )))
                                .Select(w => w.TicketNumber)))
                ).List();

在我的测试中，这生成了以下 SQL

 SELECT <snip...>
 FROM incident_details this_ 
 WHERE this_.modified_by_worker_nt_id = @p0 
    and (this_.workitem_modified_on < @p1 and this_.workitem_modified_on > @p2) 
    and this_.workitem_status_lookup_id = @p3 
    and (this_.workitem_number = @p4 
    or this_.workitem_number in 
        (SELECT this_0_.workitem_number as y0_ 
         FROM incident_details this_0_ 
         WHERE not (this_0_.workitem_status_lookup_id = this_.workitem_status_lookup_id) 
         and this_0_.workitem_number = this_.workitem_number 
         and this_0_.workitem_version = (this_.workitem_version-@p5)));
         @p0 = 'test' [Type: String (0)], @p1 = 10/26/2012 11:26:24 PM [Type: DateTime (0)], @p2 = 10/26/2012 11:26:24 PM [Type: DateTime (0)], @p3 = 1 [Type: Int32 (0)], @p4 = 1 [Type: Int32 (0)], @p5 = 1 [Type: Int32 (0)]