C#

Regex re = new Regex("\d{3}-?\d{2}-?\d-?\d{3}$");

if(!re.IsMatch(txtAccount.Text))
{
    // Display error and so on
    e.Cancel = true;
}

class DBController
{
    static DBController()
    {
        conn = new SqlConnection(....);
    }
 
    public static Customer GetCustomer(int id)
    {
        conn.Open();

        SqlCommand cmd = new SqlCommand("...", conn);
        SqlDataReader rdr = cmd.ExecuteReader();
        rdr.Read();
 
        Customer customer = new Customer()
        customer.Name = (string) rdr["Name"];

        rdr.Close();
        conn.Close();
 
        return customer;
    }

    private static SqlConnection conn;
}

try<br />
{<br />
 Form2 f2 = new Form2();<br />
 f2.ShowDialog();<br />
}<br />
catch (Exception ex)<br />
{<br />
 MessageBox.Show("Exception caught in button1_Click()\n"+ex.ToString());<br />
}