如何判断ACCESS数据库有无密码

public static bool HasPassword(string dbPathName,string currentpassword)
        {
            if (string.IsNullOrEmpty(currentpassword))
            {
                return false;
            }

            int rc = -1;
            try
            {
                string conn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Jet OLEDB:Database Password={1};Mode=Share Exclusive";
                conn = string.Format(conn, dbPathName, currentpassword);

                string sql = "ALTER DATABASE PASSWORD {0} {1}";
                sql = string.Format(sql, AccessHelper.currentpassword, currentpassword);


                using (OleDbConnection connection = new OleDbConnection(conn))
                {
                    connection.Open();
                    using (OleDbCommand command = new OleDbCommand(sql, connection))
                    {

                        rc = command.ExecuteNonQuery();
                    }
                    connection.Close();
                    return true;
                }

            }
            catch (Exception ex)
            {
                return false;
            }
        }