对象不包含标记的定义，也没有可访问的扩展方法错误

Question

我正在尝试通过单击链接标签来显示我的表中的一些数据，但是当我启动应用程序时，我有一些错误，如:对象不包含标记的定义，没有可访问的扩展方法错误

错误行:int appID = (LinkLabel)sender.Tag;

代码你请帮我解决这个错误，或者如果你有其他的想法来获得ID

下面是我的代码:

private void ShowAppointmentDetail(object sender, EventArgs e)
{
int appID = (LinkLabel)sender.Tag;
SqlCommand sql = new SqlCommand("select * from RDV whereID_RDV = {appID}");
DataTable dt = new DataTable();
SqlDataAdapter sda = new SqlDataAdapter(sql);
sda.Fill(dt);
if (dt.Rows.Count > 0)
{
DataRow row = dt.Rows[0];
{
frmManageAppointment withBlock = new frmManageAppointment();
withBlock.Nom.Text = row["Nom"].ToString();
withBlock.Prénom.Text = row["Prénom"].ToString();
withBlock.NUM.Text = row["Num"].ToString();
withBlock.date.Text = row["DateRDV"].ToString();
withBlock.ShowDialog();
}
DisplayCurrentDate();
}
}

谢谢

Answer 1

private void ShowAppointmentDetail(object sender, EventArgs e)
{
Was :  int appID = (LinkLabel)sender.Tag;
Answer :  var appID = (sender as LinkLabel).Tag;

SqlCommand sql = new SqlCommand("select * from RDV whereID_RDV = {appID}");
DataTable dt = new DataTable();
SqlDataAdapter sda = new SqlDataAdapter(sql);
sda.Fill(dt);
if (dt.Rows.Count > 0)
{
DataRow row = dt.Rows[0];
{
frmManageAppointment withBlock = new frmManageAppointment();
withBlock.Nom.Text = row["Nom"].ToString();
withBlock.Prénom.Text = row["Prénom"].ToString();
withBlock.NUM.Text = row["Num"].ToString();
withBlock.date.Text = row["DateRDV"].ToString();
withBlock.ShowDialog();
}
DisplayCurrentDate();
}
}