string connstr = "server=localhost; user=root; database=users_db; password=0000";
MySqlConnection conn = new MySqlConnection(connstr);
string sql_registrUser = "INSERT INTO `users_db`.`users` (`user_login`, `user_password`) VALUES ('" + login + "', '" + password + "');";
MySqlCommand comm_registr = new MySqlCommand(sql_registrUser, conn);

MyCommand.ExecuteNonQuery();

string sql_registrUser = "INSERT INTO `users_db`.`users` (`user_login`, `user_password`) VALUES ('" + login + "', '" + password + "');";
MySqlCommand comm_registr = new MySqlCommand(sql_registrUser, conn);
comm_registr.ExecuteNonQuery();

private OleDbConnection GetConnection()
    {
        OleDbConnectionStringBuilder oleStringBuilder = new OleDbConnectionStringBuilder();
        oleStringBuilder.Provider = "Microsoft.ACE.OLEDB.12.0";

        var currentDir = Path.GetDirectoryName(this.GetType().Assembly.Location);
        oleStringBuilder.DataSource = Path.Combine(currentDir, "wordsDb.accdb");

        OleDbConnection connection = new OleDbConnection(oleStringBuilder.ConnectionString);

        return connection;
    }

public int AddWord(Word word)
    {
        if (word == null) throw new ArgumentNullException(nameof(word));
        if (String.IsNullOrWhiteSpace(word.Eng)) throw new ArgumentException("Английское значение обязательное");
        if (String.IsNullOrWhiteSpace(word.Rus)) throw new ArgumentException("Русское значение обязательное");

        int result = 0;

        using (OleDbConnection connection = GetConnection())
        using (OleDbCommand command = connection.CreateCommand())
        {
            command.CommandText = "INSERT INTO Words (english, russian) VALUES (@eng, @rus)";
            command.Parameters.AddWithValue("eng", word.Eng);
            command.Parameters.AddWithValue("rus", word.Rus);

            connection.Open();
            result = command.ExecuteNonQuery();
        }

        return result;
    }