请大家看下我的代码哪来出错了？
在做一个系统，正在做登陆部分，因为经常要连接数据库，就自己写了个类

 public class SQLcon
    {
        private string con = "server=(local);user id=sa;password=sa;database=student";

        public SqlConnection ConnectToDatabase()
        {
            return new SqlConnection(con);
        }
        public bool Login(string uid, string pwd, SqlConnection mycon)     //判断是否登陆成功
        {
            if (mycon.State != ConnectionState.Open)
            {
                MessageBox.Show("数据库未打开");
                try
                {
                    mycon.Open();
                    SqlCommand login = new SqlCommand();
                    string str = " select UserID from UserLogin where UserName='" + uid + "' and PassWord ='" + pwd + "' ";
                    login.CommandText = str;
                    login.Connection = mycon;
                    SqlDataReader result = login.ExecuteReader();
                    mycon.Close();
                    if (result.HasRows)
                    {
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                }
                catch (Exception ex) 
 
                {
                    MessageBox.Show("数据库异常！请重试!");
                    return false;
                }
            }
            else
            {
                MessageBox.Show("数据库已经打开");
                mycon.Close();
                return false;
            }
        }

    }

而登陆按钮

        private void LoginBotton_Click(object sender, EventArgs e)
        {
            bool login = false;
            SQLcon conn = new SQLcon();
            SqlConnection newCon = conn.ConnectToDatabase();
            login = conn.Login(ID.Text.Trim(), Code.Text.Trim(),newCon);
            if (login)
            {
                MainForm form1 = new MainForm();
                form1.Show();
            }
            else
            {
                MessageBox.Show("登陆失败！");
            }

        }

执行之后，try部分没有执行，直接到catch 部分，弹出 数据库异常
请大家帮忙找出问题，谢谢
[解决办法]
把 mycon.Close();这句移到finally{}中
try
{
mycon.Open();
SqlCommand login = new SqlCommand();
string str = " select UserID from UserLogin where UserName='" + uid + "' and PassWord ='" + pwd + "' ";

login.CommandText = str;
login.Connection = mycon;
SqlDataReader result = login.ExecuteReader();
if (result.HasRows)
{
return true;
}
else
{
return false;
}
}
catch (Exception ex)
{
MessageBox.Show("数据库异常！请重试!");
return false;
}
finally
{ mycon.Close();}