private void btn_edit_Click(object sender, EventArgs e)
 {
     if (customerInfoBindingSource.Current == null)
     {
         return;
     }
     using (Form_addctm frm = new Form_addctm(customerInfoBindingSource.Current as CustomerInfo))
     {
         if (frm.ShowDialog() == DialogResult.OK)
         {
             customerInfoBindingSource.DataSource = db.CustomerInfoes.ToList();
         }
     }
 }
 private void btn_newctm_Click(object sender, EventArgs e)
 {
     if (customerInfoBindingSource.Current == null)
     {
         return;
     }
     using (Form_addctm frm = new Form_addctm(null))
     {
         if (frm.ShowDialog() == DialogResult.OK)
         {
             customerInfoBindingSource.DataSource = db.CustomerInfoes.ToList();
         }
         dataGridView1.Refresh();
     }
 }