using queryexpression in c# to retreieve data

to retrieve data from crm  2011
we can use queryexpression.
first create condition expression.
then filter expression.
then query expression.

this code for login credential checking in crm 2011.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;
using System.ServiceModel.Description;
using System.Net;
using Microsoft.Xrm.Sdk;
using Microsoft.Xrm.Sdk.Client;
using System.Data;
using System.Data.SqlClient;
using Microsoft.Xrm.Sdk.Query;
using System.Configuration;
using Sulekha.Order.CrmSdk;
using System.Linq.Expressions;
using Xrm;
using System.Data.SqlClient;
using System.Configuration;


namespace Sulekha.Order
{
    public partial class Login : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            //SqlConnection con = new

            Entity contacts = new Entity("contact");


            string user = username.Text.ToString();
            string pass = password.Text.ToString();

           
       

            ClientCredentials credentials = new ClientCredentials();
            credentials.Windows.ClientCredential = CredentialCache.DefaultNetworkCredentials;
            Uri OrganizationUri = new Uri("http://crmserver/databaseCRM/XRMServices/2011/Organization.svc");
            Uri HomeRealmUri = null;
            using (OrganizationServiceProxy serviceProxy = new OrganizationServiceProxy(OrganizationUri, HomeRealmUri, credentials, null))
            {
                Microsoft.Xrm.Sdk.IOrganizationService service = (Microsoft.Xrm.Sdk.IOrganizationService)serviceProxy;

              


                ConditionExpression condition = new ConditionExpression();
                condition.AttributeName = "firstname";
                condition.Operator = ConditionOperator.Equal;
                condition.Values.Add(user);

                ConditionExpression condition1 = new ConditionExpression();
                condition1.AttributeName = "lastname";
                condition1.Operator = ConditionOperator.Equal;
                condition1.Values.Add(pass);

                FilterExpression filter1 = new FilterExpression();
                filter1.Conditions.Add(condition);
                filter1.Conditions.Add(condition1);

                QueryExpression query = new QueryExpression("contact");
                query.ColumnSet.AddColumns("firstname", "lastname");
                query.Criteria.AddFilter(filter1);
               

                EntityCollection result1 = serviceProxy.RetrieveMultiple(query);

                if (result1.Entities.Count > 0)
                {
                    ClientScript.RegisterStartupScript(Page.GetType(), "validation", "<script language='javascript'>alert('valid Username and Password')</script>");

                }
                else
                {
                    ClientScript.RegisterStartupScript(Page.GetType(), "validation", "<script language='javascript'>alert('invalid Username and Password')</script>");
                }                  



            
               

            }
        }
    }
}

ref :

http://mileyja.blogspot.in/2011/07/convert-queryexpression-to-fetchxml.html

http://stackoverflow.com/questions/8669611/how-to-write-queryexpression-for-following-query

http://msdn.microsoft.com/en-us/library/gg334688.aspx


OptionSetValue osv = (OptionSetValue)entities.Attributes["statuscode"];
                        if (osv.Value == 1)
                        {
                            dr["Order Status"] = "New";
                        }
                        if (osv.Value == 2)
                        {
                            dr["Order Status"] = "Pending";
                        }


                        //dr["Order Status"] = osv.Value;
for optional set value