的DevExpress XPO與子查詢

Question

我已經打破了我的腦海裏嘗試使用XPO寫下一MSSQL查詢：

SELECT  Gate.Name, grp.maxDate as 'Latest pass', a.Type, a.ReceivedTime as 'Imported at' 
FROM  Access AS a INNER JOIN 
         (SELECT  GateId, MAX(OpenTime) AS maxDate 
         FROM  Access 
         GROUP BY GateId) AS grp ON a.GateId = grp.GateId AND a.OpenTime = grp.maxDate INNER JOIN 
        Gate ON a.GateId = Gate.ID 
        order by Gate.ID 

我Access表中有大約2條磨記錄，但它只有40個不同GATEID的。我要選擇各門線，這將是這樣的：
GateName                的OpenTime                類型               在
進口... .................................................. ...............................
Supergate                 20/09/2013                                     21/09/2013
Ultragate                 19/09/2013                                     22/09/2013

我訪問類看起來是這樣的：

public partial class Access : XPLiteObject 
{ 
    Gate fGateId; 
    [Association(@"AccessReferencesGate")] 
    public Gate GateId 
    { 
     get { return fGateId; } 
     set { SetPropertyValue<Gate>("GateId", ref fGateId, value); } 
    } 
    DateTime fOpenTime; 
    public DateTime OpenTime 
    { 
     get { return fOpenTime; } 
     set { SetPropertyValue<DateTime>("OpenTime", ref fOpenTime, value); } 
    } 
    byte fType; 
    public byte Type 
    { 
     get { return fType; } 
     set { SetPropertyValue<byte>("Type", ref fType, value); } 
    } 
    DateTime fReceivedTime; 
    public DateTime ReceivedTime 
    { 
     get { return fReceivedTime; } 
     set { SetPropertyValue<DateTime>("ReceivedTime", ref fReceivedTime, value); } 
    } 
    int fID; 
    [Key(true)] 
    public int ID 
    { 
     get { return fID; } 
     set { SetPropertyValue<int>("ID", ref fID, value); } 
    } 
    public Access(Session session) : base(session) { } 
} 

我的門類：

public partial class Gate : XPLiteObject 
{ 
    int fID; 
    [Key(true)] 
    public int ID 
    { 
     get { return fID; } 
     set { SetPropertyValue<int>("ID", ref fID, value); } 
    } 
    string fName; 
    [Size(20)] 
    public string Name 
    { 
     get { return fName; } 
     set { SetPropertyValue<string>("Name", ref fName, value); } 
    } 
    } 
    [Association(@"AccessReferencesGate", typeof(Access))] 
    public XPCollection<Access> AccessCollection { get { return GetCollection<Access>("AccessCollection"); } } 
    public Gate(Session session) : base(session) { } 
} 

任何答案，甚至RTFM鏈接將不勝感激！從DevExpress的支持中心

Answer 1

答案，爲我工作：

XPView view = new XPView(typeof(Access)); 
view.AddProperty("Name", "GateId.Name"); 
view.AddProperty("LatestPass", "[<Access>][GateId = ^.GateId].Max(OpenTime)"); 
view.AddProperty("Type", "Type"); 
view.AddProperty("ImportedAt", "ReceivedTime"); 
view.Criteria = CriteriaOperator.Parse("OpenTime = [<Access>][GateId = ^.GateId].Max(OpenTime)"); 

Answer 2

喜歡的東西

var accesses = new XPQuery<Access>(session); 
var result = 
    from a in accesses 
    where a.OpenTime == a.GateId.AccessCollection.Max(b => b.OpenTime) 
    select new { a.GateId.Name, a.Type, a.ReceivedTime };