DbProviderFactory

static DbConnection CreateDbConnection(string providerName, string connectionString)
{
    DbConnection connection = null;

    if (connectionString != null)
    {
        try
        {
            DbProviderFactory factory = DbProviderFactories.GetFactory(providerName);

            connection = factory.CreateConnection();
            connection.ConnectionString = connectionString;
        }
        catch (Exception ex)
        {
            if (connection != null)
            {
                connection = null;
            }
        }
    }
    return connection;
}

http://msdn.microsoft.com/ko-kr/library/dd0w4a2z%28v=vs.110%29.aspx