IF Countryid = 1 Country= USA then
When we Bind dropdownlist then it bind SelectedItem.Value As 1 and SelectedItem.Text as USA.
When we use COOB.Text.Trim(); it return is SelectedValue text as 1 you need to use COOB.SelectedItem.TextTrim(); to get USA as selectedTextvalue
In protected void UpdateButton_Click(object sender, EventArgs e) Event
/* Replace the Below Code line */
cmd.Parameters.Add("@COB", SqlDbType.VarChar).Value = COB.Text.Trim();
cmd.Parameters.Add("@SOB", SqlDbType.VarChar).Value = SOB.Text.Trim();
cmd.Parameters.Add("@COOB", SqlDbType.VarChar).Value = COOB.Text.Trim();
/* As */
cmd.Parameters.Add("@COB", SqlDbType.VarChar).Value = COB.SelectedItem.Text.Trim();
cmd.Parameters.Add("@SOB", SqlDbType.VarChar).Value = SOB.SelectedItem.TextTrim();
cmd.Parameters.Add("@COOB", SqlDbType.VarChar).Value = COOB.SelectedItem.TextTrim();