MGZ NetArt

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Data;

using System.Data.SqlClient;

using System.Data.Odbc;

using System.Data.OleDb;

namespace ConnectionFactory {

    enum DataProvider { SqlServer, OleDb, Odbc, None }

    public class ConnectionSingletone {

        private static IDbConnection instance;

        private ConnectionSingletone() { }

        static IDbConnection GetConnection(DataProvider dp) {

            if (instance == null) {

                switch (dp) {

                    case DataProvider.SqlServer:

                        instance = new SqlConnection();

                        break;

                    case DataProvider.Odbc:

                        instance = new OdbcConnection();

                        break;

                    case DataProvider.OleDb:

                        instance = new OleDbConnection();

                        break;

                }

            }

            return instance;

        }

    }

}

references:

msdn singletone

Singletone pattern