Auto complete extender in dotnet

[System.Web.Services.WebMethodAttribute(), System.Web.Script.Services.ScriptMethodAttribute()]

   public static List<string> GetCompletionList(string prefixText, int count, string contextKey)

   {

       List<string> s1 = new List<string>();

       SqlConnection cn = new SqlConnection(@"Data Source=ammiforu;Initial Catalog=mail;Integrated Security=True");

       SqlCommand cmd = new SqlCommand("select email from fgetpass where email like @p1+'%'", cn);

       cmd.Parameters.AddWithValue("@p1", prefixText);

       cn.Open();

       SqlDataReader dr = cmd.ExecuteReader();

       while (dr.Read())

       {

           s1.Add(dr[0].ToString());

       }

       return s1;