WebService for Checking UserName

Here is the solution for checking UserName availability using web service with AJAX enabled page method...

place the following script in head tag....

Script :

<script type="text/javascript">
        var usernameCheckerTimer;
        function usernameChecker(username) {
            var spanAvailability = $get("spanAvailability");
            clearTimeout(usernameCheckerTimer);
            if (username == "") {
                spanAvailability.innerHTML = "Code cannot be Blank";
            }
            else {
                spanAvailability.innerHTML = "checking...";
                usernameCheckerTimer = setTimeout("checkUsernameUsage('" + username + "');", 750);
            }
        }

        function checkUsernameUsage(username) {
            PageMethods.IsUserAvailable(username, OnSucceeded);
        }
        function OnSucceeded(result, userContext, methodName) {
            var spanAvailability = $get("spanAvailability");
            if (methodName == "IsUserAvailable") {
                if (result == true)
                    spanAvailability.innerHTML = "Already Exists";
                else
                    spanAvailability.innerHTML = "Does Not Exist";
            }
        }
    </script>

Place the following design code with in the form tag...

Design :

<asp:ScriptManager ID="ScriptManager1" EnablePageMethods="true" runat="server">
   </asp:ScriptManager>
   <div>
       <table>
           <tr>
               <td>
                   User Name
               </td>
               <td>
                   <asp:TextBox ID="TextBox1" runat="server" onblur="usernameChecker(this.value);"></asp:TextBox>
                   <span id="spanAvailability"></span>
               </td>
           </tr>
       </table>
   </div>

Code Behind :

protected void Page_Load(object sender, EventArgs e)
    {

    }
    [WebMethod]
    public static bool IsUserAvailable(string username)
    {
        using (SqlConnection con = new SqlConnection(@"Data Source=maj-056\sqlexpress;Initial Catalog=Sample;Integrated Security=True;Pooling=False"))
        {
            con.Open();
            SqlCommand cmd = new SqlCommand("select * from tblLogin where UserName='" + username + "'", con);
            SqlDataReader dr = cmd.ExecuteReader();
            if (dr.Read())
            {
                return true;
            }
            else
            {
                return false;
            }
            con.Close();
        }
    }