Check username with Ajax using PageMethod

Ajax PageMethod

MS AJAX has gone one step further! We can now call methods in the codebehind of the current page from Javascript. Here's how:

Here i am tryin to Check whether the USERNAME Exists in my database.

----- Default.aspx

<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePageMethods="True" />
<asp:TextBox ID="TxtEventCode" runat="server" CssClass="StyleTextForm"
onblur="usernameChecker(this.value);"></asp:TextBox>
<span id ="spanAvailability"></span>

JavaScript part with the Script tag.

<script type="text/javascript">
var usernameCheckerTimer;
var spanAvailability = $get("spanAvailability");

function usernameChecker(username) {
clearTimeout(usernameCheckerTimer);
if (username == "")
//if (username.length == 0)
spanAvailability.innerHTML = "Code cannot be Blank";
else {
spanAvailability.innerHTML = "checking...";
usernameCheckerTimer = setTimeout("checkUsernameUsage('" + username + "');", 750);
}
}

function checkUsernameUsage(username) {
// initiate the ajax pagemethod call
// upon completion, the OnSucceded callback will be executed
PageMethods.IsUserAvailable(username, OnSucceeded);
}

// Callback function invoked on successful completion of the page method.
function OnSucceeded(result, userContext, methodName) {
if (methodName == "IsUserAvailable") {
if (result == true)
//spanAvailability.innerHTML = "Available";
spanAvailability.innerHTML = "Already Exists";
else
spanAvailability.innerHTML = "Does Not Exist";
}
}
</script>

***** Do not forget to set the EnablePageMethods attribute to true. ******

------- Default.aspx.cs

using System;
using System.Data;
using System.Data.SqlClient;
using System.Web.Services;

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

}
using System.Web.Services;

[WebMethod]
public static bool IsUserAvailable(string username)
{
SqlConnection cnn = new SqlConnection("data source=SYSTEMNAME; initial catalog=EVENTMGM; user ID=xxxx; Password=xxxx");
string Sqlstr;
//SqlCommand cmd = new SqlCommand();
//cmd.Connection= cnn;
//cmd.CommandType = CommandType.Text;
Sqlstr="SELECT USERNAME FROM USERLOG WHERE CODE = '" + username + "' ";
SqlDataAdapter da = new SqlDataAdapter(Sqlstr, cnn);
DataSet ds = new DataSet();
da.Fill(ds, "USERLOG");
//cmd.CommandText= Sqlstr;
//cnn.Open();
//int cnt = cmd.ExecuteNonQuery();

//cnn.Close();

if ( ds.Tables["HOTELMAS"].Rows.Count > 0)
return true;
else
return false;

//if (username.ToLower() == "travis")
// return false;
//else
// return true;
}
}
}