Silverlight 如何使用客户端对象模型从Sharepoint server 2010检索最大日期和最小日期？

我正在开发silverlight web部件。我有一个列表条目日志。在这个列表中，我存储了基本信息的所有条目。所有条目都已成功保存。现在，我想在条目日志列表中检索创建这些条目的最大日期和最小日期。因此，我使用以下代码

    public void PopulateTimeLog(String paymentStatus, String currentUser, timeLogDelegate populateCombo)
    {
        timeLogDelegateClient = populateCombo;

        ClientContext clientContext = ClientContext.Current;
        List list = clientContext.Web.Lists.GetByTitle("Time Log");

        string query = "<View>";
        query += "<Query>";
        query += "<Where>";
        query += "<And>";
        query += "<Eq>";
        query += "<FieldRef Name='Author'></FieldRef>";
        query += "<Value Type='Lookup'>" + currentUser + "</Value>";
        query += "</Eq>";
        query += "<Eq>";
        query += "<FieldRef Name='Payment_x0020_Status'></FieldRef>";
        query += "<Value Type='Text'>" + paymentStatus + "</Value>";
        query += "</Eq>";
        query += "</And>";
        query += "</Where>";
        query += "<OrderBy>";
        query += "<FieldRef Name='Created' Ascending='False'></FieldRef>";
        query += "</OrderBy>";                       
        query += "</Query>";
        query += "</View>";            

        CamlQuery Query = new CamlQuery();
        Query.ViewXml = query;

        listItemsTimeLog = list.GetItems(Query);
        //clientContext.Load(list);
        //clientContext.Load(listItemsTimeLog);

        clientContext.Load(listItemsTimeLog, itms => itms.Include(
                                                        itm => itm["Created"]));


        clientContext.ExecuteQueryAsync(HandleTimeLogRequestSucceeded, HandleTimeLogRequestFailed);

    }

    private void HandleTimeLogRequestSucceeded(object sender, ClientRequestSucceededEventArgs e)
    {
        ////call back on the UI thread
        System.Windows.Deployment.Current.Dispatcher.BeginInvoke(() =>
        {

            timeLogDelegateClient(listItemsTimeLog);
        });
    }

在上面的代码中，我将在索引0处获取listItemsTimeLog中的最大日期，在最后一个索引处获取listItemsTimeLog中的最小日期。在上面的查询中，我不想检索listItemsTimeLog中的所有日期。如何简化上述查询，以便只获得两个字符串值—一个字符串包含最大日期，另一个字符串包含最小日期。如果我能通过网络服务做到这一点，那么对我来说也没问题吧？我该怎么做？你能给我提供一些代码让我解决上面的问题吗？

你可以用它，例如

马克斯

闵

<View>
  <Query>
    <Where>
      <And>
        <Eq>
          <FieldRef Name='Author'></FieldRef>
          <Value Type='Lookup'>[your use name]</Value>
        </Eq>
        <Eq>
          <FieldRef Name='Payment_x0020_Status'></FieldRef>
          <Value Type='Text'>[ your payment status]</Value>
        </Eq>
      </And>
    </Where>
    <OrderBy>
      <FieldRef Name='Created' Ascending='False'></FieldRef>
    </OrderBy>
  </Query>
 <RowLimit>1</RowLimit>
</View>

<View>
  <Query>
    <Where>
      <And>
        <Eq>
          <FieldRef Name='Author'></FieldRef>
          <Value Type='Lookup'>[your use name]</Value>
        </Eq>
        <Eq>
          <FieldRef Name='Payment_x0020_Status'></FieldRef>
          <Value Type='Text'>[ your payment status]</Value>
        </Eq>
      </And>
    </Where>
    <OrderBy>
      <FieldRef Name='Created' Ascending='True'></FieldRef>
    </OrderBy>
  </Query>
 <RowLimit>1</RowLimit>
</View>