using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        Factory f = new Factory(new MSSQLFactory());

        f.Connect();

        f.Execute();

        f.Disconnect();

        Console.WriteLine("################");

        f = new Factory(new OracleFactory());

        f.Connect();

        f.Execute();

        f.Disconnect();

    }

}

​

public class Factory

{

    private readonly DatabaseFactory _dbfac;

    private readonly IConnection _connection;

    private readonly ICommand _command;

    public Factory(DatabaseFactory dbfac)

    {

        _dbfac= dbfac;

        _connection = dbfac.CreateConnection();

        _command = dbfac.CreateCommand();

    }

    public void Connect()

    {

        _connection.Connect();

    }

    public void Disconnect()

    {

        _connection.Disconnect();

    }

    public void Execute()

    {

        _command.Execute();

    }

}

​

public abstract class DatabaseFactory

{

    public abstract IConnection CreateConnection();

    public abstract ICommand CreateCommand();

}

​

public class MSSQLFactory : DatabaseFactory

{

    public override IConnection CreateConnection()

    {

        return new MSSQLConnection();

    }

    public override ICommand CreateCommand()

    {

        return new MSSQLCommand();

    }

}

​

public class OracleFactory : DatabaseFactory

{

    public override IConnection CreateConnection()

    {

        return new OracleConnection();

    }

    public override ICommand CreateCommand()

    {

        return new OracleCommand();

    }

}

​

public interface IConnection

{

    void Connect();

    void Disconnect();

}

​

public class MSSQLConnection : IConnection

{

    public void Connect()

    {

        Console.WriteLine("Connected MSSQL database started..");

    }

    public void Disconnect()

    {   

        Console.WriteLine("Disconnected MSSQL database stopped.");

    }

}

​

public class OracleConnection : IConnection

{

    public void Connect()

    {

        Console.WriteLine("Connected Oracle database started..");

    }

    public void Disconnect()

    {

        Console.WriteLine("Disconnected Oracle database stopped.");

    }

}

​

​

public interface ICommand

{

    void Execute();

}

​

public class MSSQLCommand : ICommand

{

    public void Execute()

    {

        Console.WriteLine("MSSQL query running...");

    }

}

​

public class OracleCommand : ICommand

{

    public void Execute()

    {

        Console.WriteLine("Oracle query running...");

    }

}