How to retrieve the maximum date and minimum date from Sharepoint server 2010 using client object model?

Question

I am developing silverlight web part. I have a one List Entry log. In this list I am storing all the entries of basic information. All the entries are saved successfully. Now I want to retrieve the maximum date and minimum date on which these entries are created in the Entry log list. So I am using the following code

    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);
        });
    }

In the above code I will get the the maximum date in listItemsTimeLog at index 0 and minimum date in listItemsTimeLog at last index. In the above query i dont want to retrieve all the dates in the listItemsTimeLog. How Can I simplify the above query so that I will get only two string values - One string will contain maximum date and other string will contain mimimum date . If I can do it through web service then it is also fine for me ? How can I do this ? Can you please provide me any code so that I can solve the above issue ?

Answer 1

You can use RowLimit for this, e.g.

Max

<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>

Min

<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>