Code to bind gridview with DataAdapter

protected void Page_Load(object sender, EventArgs e)
{
        if (!IsPostBack)
        {
            bindRecord();
        }

}
Public void bindRecord()
{
    SqlConnection con =new SqlConnection(ConfigurationManager.
           ConnectionStrings["ConnectionString"].ConnectionString.ToString();)
    SqlCommand cmd=new SqlCommand();
    cmd.connection=con;
    con.open();
    cmd.commandText="SELECT * FROM tablename";
    SqlDataAdapter da=new SqlDataAdapter(cmd);
    Dataset ds=new Dataset();
    da.fill(ds);
    cmd.ExecuteNonQuery();
    grdview.DataSource=ds;
    grdview.DataBind();
    con.close();


}