Method return an interface

IDataReader myReader = questDatabase.ExecuteReader(getQuest);

IDbCommand command = GiveMeSomeCommand();
IDataReader r = command.ExecuteReader();

private static IDbCommand GiveMeSomeCommand()
{
    return new OleDbCommand();
}

private static IDbCommand GiveMeSomeCommand()
{
    return new SqlCommand();
}

DbProviderFactory factory = GiveMeSomeFactory();
IDbCommand command = factory.CreateCommand();
IDataReader r = command.ExecuteReader();

//and create more objects
IDataAdapter adapter = factory.CreateDataAdapter();
IDbConnection conn = factory.CreateConnection();

private DbProviderFactory GiveMeSomeFactory()
{
    if(something)
        return SqlClientFactory.Instance;
    else if(somethingElse)
        return OracleFactory.Instance;
    else if(notThisAndNotThat)
        return MySqlFactory.Instance;
    else
        return WhateverFactory.Instance;

}