Find Method的Keys Collection出来了

Question

当我在浏览器上单击“更新”按钮后进行调试时，它会在GridView1_RowUpdating中的以下行引发NullReferenceException：

dr["Phone Number"] = e.NewValues["Phone Number"];

完整代码：

public partial class DataBound : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e) { }

    private void getCacheData()
    {
        if (Cache["DATASET"] != null)
        {
            GridView1.DataSource = Cache["DATASET"];
            GridView1.DataBind();
        }
    }

    private void getDataDB()
    {
        String connectionString = ConfigurationManager.ConnectionStrings["MySqlConnectionString"].ConnectionString;
        MySqlConnection con = new MySqlConnection(connectionString);
        MySqlDataAdapter adp = new MySqlDataAdapter("select `Customer ID`,`Customer Name`,`Phone Number` from customer", con);
        DataSet ds = new DataSet();
        adp.Fill(ds, "Customer");
        ds.Tables["Customer"].PrimaryKey = new DataColumn[] { ds.Tables["Customer"].Columns["Customer ID"] };
        Cache.Insert("DATASET", ds, null, DateTime.UtcNow.AddHours(24), System.Web.Caching.Cache.NoSlidingExpiration);
        GridView1.DataSource = ds;
        GridView1.DataBind();
    }

    protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
    {
        GridView1.EditIndex = e.NewEditIndex;
        getCacheData();
    }

    protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {
        try
        {
            DataSet ds = (DataSet)Cache["DATASET"];
            DataRow dr = ds.Tables["Customer"].Rows.Find(e.Keys["Customer ID"]);
            dr["Phone Number"] = e.NewValues["Phone Number"];
            dr["Customer Name"] = e.NewValues["Customer Name"];
            Cache.Insert("DATASET", ds, null, DateTime.UtcNow.AddHours(24), System.Web.Caching.Cache.NoSlidingExpiration);
            GridView1.EditIndex = -1;
            getCacheData();
        }
        catch (Exception ex)
        {
            String errorMessage = ex.Message;
        }
    }

    protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
    {
        GridView1.EditIndex = -1;
        getCacheData();
    }

    protected void btnGetDataDB_Click(object sender, EventArgs e)
    {
        getDataDB();
    }
}