autocomplete datagridview in c#

Quote:

<asp:textbox id="username" textmode="SingleLine" runat="server" xmlns:asp="#unknown">
ToolTip="Enter username" AutoCompleteType="DisplayName" Height="22px">
<ajax:autocompleteextender id="AutoCompleteExtender1" runat="server" targetcontrolid="username" xmlns:ajax="#unknown">
MinimumPrefixLength="1" EnableCaching="true" CompletionSetCount="1" CompletionInterval="1000" ServiceMethod="GetCountries" >

Quote:

[System.Web.Script.Services.ScriptMethod()]
[System.Web.Services.WebMethod]
public static List<string> GetCountries(string prefixText)
{
SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["schoolconn"].ToString());
con.Open();
SqlCommand cmd = new SqlCommand("select * from login_details where username like @Name+'%'", con);
cmd.Parameters.AddWithValue("@Name", prefixText);
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataTable dt = new DataTable();
da.Fill(dt);
List<string> CountryNames = new List<string>();
for (int i = 0; i < dt.Rows.Count; i++)
{
CountryNames.Add(dt.Rows[i][2].ToString());
}
return CountryNames;
}