SOLID principle - Single responsability - Good example

connection.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Threading.Tasks;
using MySql.Data.MySqlClient;

namespace MyDataManipulationApp{
	public class Connection{
		private string serverIp;
		private string databaseName;
		private string userName;
		private string userPassword;
		private MySqlConnection connection;
		private MySqlCommand query;
		private MySqlDataReader dataReader;

		private void connect(){
			this.connection = new MySqlConnection(
	                "server=" + this.serverIp + ";" +
	                "userid=" + this.userName + ";" +
	                "password=" + this.userPassword + ";" +
	                "database=" + this.databaseName + ";" 
	            );
			this.connection.open();
			this.command = this.connection;
		}
	}
}

file.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Threading.Tasks;
using MySql.Data.MySqlClient;

namespace MyDataManipulationApp{
	public class FileWriter{
		private string fileName;
		public void WriteFile(){
			this.fileName = @"C:\temp\activeProducts.txt";

			Products p = new Products();

			foreach(string row in p.GetInformation()){
				File.WriteAllText(
					fileName,
					row["id"].toString() +
					row["name"].toString() +
					row["stock"].toString() +
					row["description"].toString() +
					Environment.NewLine
				);		
			}
		}
	}
}

products.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Threading.Tasks;
using MySql.Data.MySqlClient;

namespace MyDataManipulationApp{
	public class Products{
        // Constructor of the class
        public void Products(){
            this.connect();
        }
		public List<string> GetInformation(){
			this.command = "SELECT id,name,stock,description from products WHERE active;";
			this.dataReader = this.command.ExecuteReader();
            List<string> list = (
                from IDataRecord r in this.dataReader
                select (string)r["FieldName"]
            ).ToList();
            return list;
		}
	}
}