PHP - a DB abstraction layer use static class vs singleton object?

Question

I don\'t want to create a discussion about singleton better than static or better than global, etc. I read dozens of questions about similar subjects on SO, but I couldn\'t

Answer 1

What is wrong with the following (simplified) example:

class Database
{
    protected $_connection;

    protected $_config;

    public function __construct( array $config ) // or other means of passing config vars
    {
        $this->_config = $config;
    }

    public function query( $query )
    {
        // use lazy loading getter
        return $this->_getConnection()->query( $query );
    }

    protected function _getConnection()
    {
        // lazy load connection
        if( $this->_connection === null )
        {
            $dsn = /* create valid dsn string from $this->_config */;

            try
            {
                $this->_connection = new PDO( $dsn, $this->_config[ 'username' ], $this->_config[ 'password' ] );
            }
            catch( PDOException $e )
            {
                /* handle failed connecting */
            }
        }

        return $this->_connection;
    }
}

$db1 = new Database( array(
    'driver'   => 'mysql',
    'host'     => 'localhost',
    'dbname'   => 'test',
    'username' => 'test_root',
    'password' => '**********'
) );

$db2 = new Database( array(
    'driver'   => 'pgsql',
    'host'     => '213.222.1.43',
    'dbname'   => 'otherdb',
    'username' => 'otherdb_root',
    'password' => '**********'
) );

$someModel       = new SomeModel( $db1 );
$someOtherModel  = new SomeOtherModel( $db2 );
$yetAnotherModel = new YetAnotherModel( $db2 );

This demonstrates how you can make use of lazy loading connections, and still have flexibility to use different database connections.

The database instances will only connect to their individual connection when an object that consumes one of the instances (in this case one of the models) decides to call a method of the instance.