I assume that you can update more than one record by selecting multiple check box.
On Submit buttons click event make following code.
for (int i = 0; i < grdDisplayAll.Rows.Count; i++)
{
string id;
if (Convert.ToBoolean(grdDisplayAll.Rows[i].Cells[0].Value) == true)
{
id = grdDisplayAll.Rows[i].Cells["Id"].Value.ToString();
}
}
Mark as
Answer/Solution if it is helpful to you. :-O :)