Using Ajax to check username availability in ASP.NET

By deepz on Apr 22nd, 2011 2:18 pm

Hi,
This code checks the availability of username from the database.

Default.aspx

<%@ Register Namespace="AjaxControlToolkit" Assembly="AjaxControlToolkit" tagPrefix="ajax" %>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>Check Username availability Using Ajax</title>
</head>
<body>
<form id="form1" runat="server">
<asp:ScriptManager ID="scriptmanager1" runat="server">
</asp:ScriptManager>
<div>
<asp:UpdatePanel ID="PnlUsrDetails" runat="server">
<ContentTemplate>
<table>
<tr>
<td>
UserName:
</td>
<td>
<asp:TextBox ID="txtUsername" runat="server" AutoPostBack="true" ontextchanged="txtUsername_TextChanged"/>
</td>
<td>
<div id="checkusername" runat="server"  Visible="false">
<asp:Image ID="imgstatus" runat="server" Width="17px" Height="17px"/>
<asp:Label ID="lblStatus" runat="server"></asp:Label>
</div>
</td>
</tr>
</table>
</ContentTemplate>
</asp:UpdatePanel>
</div>
</form>
</body>
</html>

Default.aspx.cs

using System.Data.SqlClient;

protected void txtUsername_TextChanged(object sender, EventArgs e)
{
if (!string.IsNullOrEmpty(txtUsername.Text))
{
SqlConnection con = new SqlConnection("your connection string");
con.Open();
SqlCommand cmd = new SqlCommand("select * from UserInformation where UserName=@Name", con);
cmd.Parameters.AddWithValue("@Name", txtUsername.Text);
SqlDataReader dr = cmd.ExecuteReader();
if (dr.HasRows)
{
checkusername.Visible = true;
imgstatus.ImageUrl = "NotAvailable.jpg";
lblStatus.Text = "UserName Already Taken";
}
else
{
checkusername.Visible = true;
imgstatus.ImageUrl = "Icon_Available.gif";
lblStatus.Text = "UserName Available";
}
}
else
{
checkusername.Visible = false;
}
}

1 Year Ago