using System;

using System.Collections.Generic;

​

namespace DatabaseConnectionExample

{

    public class PostgreSQLDB

    {

        public void Connect()

        {

            Console.WriteLine("Connecting to PostgreSQL database");

        }

    }

​

    public class SQLiteDatabase

    {

        public void Connect()

        {

            Console.WriteLine("Connecting to SQLite database");

        }

    }

​

    public class MSSQLServerDB

    {

        public void Connect()

        {

            throw new Exception("Cannot connect to MSSQL Server");

        }

    }

​

    class Program

    {

        public static void ConnectToMSSQLServerDatabase(MSSQLServerDB db)

        {

            try

            {

                db.Connect();

                Console.WriteLine($"Successfully connected to {db.GetType().Name}\n");

            }

            catch (Exception ex)

            {

                Console.WriteLine($"Error connecting to database: {ex.Message}\n");

            }

        }

​

        public static void ConnectToPostgreSQLDatabase(PostgreSQLDB db)

        {

            try

            {

                db.Connect();

                Console.WriteLine($"Successfully connected to {db.GetType().Name}\n");

            }

            catch (Exception ex)

            {

                Console.WriteLine($"Error connecting to database: {ex.Message}\n");

            }

        }

​

        public static void ConnectToSQLiteDatabase(SQLiteDatabase db)

        {

            try

            {

                db.Connect();

                Console.WriteLine($"Successfully connected to {db.GetType().Name}\n");

            }

            catch (Exception ex)

            {

                Console.WriteLine($"Error connecting to database: {ex.Message}\n");

            }

        }

​

        static void Main(string[] args)

        {

            // Create a list of databases to connect to

            List<object> databases = new List<object>()

            {new PostgreSQLDB(), new SQLiteDatabase(), new MSSQLServerDB()};

            // Loop through the list and call the appropriate connect method for each database

            foreach (var db in databases)

            {

                if (db is PostgreSQLDB)

                {

                    ConnectToPostgreSQLDatabase((PostgreSQLDB)db);

                }

                else if (db is SQLiteDatabase)

                {

                    ConnectToSQLiteDatabase((SQLiteDatabase)db);

                }

                else if (db is MSSQLServerDB)

                {

                    ConnectToMSSQLServerDatabase((MSSQLServerDB)db);

                }

            }

        }

    }

}