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PHP5 Database Objects Using Singleton Pattern

PHP5 Database Objects Using Singleton Pattern

this code is by far complete, it contains a few functions to help you on your way.  This shows a good example of how Sqlite is used. 
I have also shown how to extend classes (Database class is extended to both Sqlite and Myql classes although they could be stand alone)  If you know PHP5 well please comment with any suggestions you come up with on how to make this code better. 

index.php 

<? 
// the following code will make it so that the class directory is in your include_path 
// this allows the __autoload function to work. 
$cur = ini_get("include_path"); 
$cur .= PATH_SEPARATOR.dirname(__FILE__).'\\include\\class\\';; 
ini_set("include_path", $cur); 

// this will load any classes that are not found and are located in the 
// /include/class/ folder. 

function __autoload($class) { 
    include($class . '.php'); 

    /* Check to see it the include defined the class */ 
    if ( !class_exists($class, false) ) { 
        trigger_error("Unable to load class $class", E_USER_ERROR); 
    } 
} 


// get an instance of the sqlite database 
$db = Sqlite::getInstance('mysqlitedb', 0666); 
$db->Open(); 
$db->Create(); 
$result = $db->Query('SELECT * FROM states'); 
$arr = $db->FetchAll($result); 

echo '<pre>'; 
print_r($arr); 
echo '</pre>'; 

/* 
// this is how you would use the Mysql class 

$db1 = Mysql::getInstance('localhost', 'mydb', 'user', 'password'); 
$db1->Open(); 
$result = $db1->Query("SELECT * FROM table"); 
$arr1 = $db1->FetchArray($result); 

echo '<pre>'; 
print_r($arr1); 
echo '</pre>'; 

*/ 

?> 

/include/class/Database.php 

<? 
class Database { 
    // an array of properties used by __get and __set 
    private $props; 
     
    // the actual connection resource 
    protected $connection; 
     
    // the hostname for the database server 
    protected $hostname; 
     
    // the name of the database to use 
    protected $database; 
     
    // the username to use to access the database 
    protected $username; 
     
    // the password to use to access the database 
    protected $password; 
     
    private function __construct($dbHost=null, $dbName=null, $dbUser=null, $dbPass=null) { 
        $this->database = $dbName; 
        $this->hostname = $dbHost; 
        $this->username = $dbUser; 
        $this->password = $dbPass; 
    } 
     
    protected function __set($name, $value) { 
        if (isset($this->props[$name])) { 
            $this->props[$name] = $value; 
        } 
    } 
     
    protected function __get($name) { 
        if (isset($this->props[$name])) { 
            return $this->props[$name]; 
        } else { 
            return nulll;     
        } 
    } 
} 
?> 

/include/class/Mysql.php 

<? 

class Mysql extends Database { 

    static private $instance; 

    public function __construct($dbHost=null, $dbName=null, $dbUser=null, $dbPass=null) { 
        parent::__construct($dbHost, $dbName, $dbUser, $dbPass); 
    } 

    static function getInstance($dbHost, $dbName, $dbUser, $dbPass) { 
        if(!Mysql::$instance) { 
            Mysql::$instance = new Mysql($dbHost, $dbName, $dbUser, $dbPass); 
        } 
        return Mysql::$instance; 
    } 

    public function __set($name, $value) { 
        if (isset($name) && isset($value)) { 
            parent::__set($name, $value); 
        } 
    } 

    public function __get($name) { 
        if (isset($name)) { 
            return parent::__get($name); 
        } 
    } 

    public function Connected() { 
        if (is_resource($this->connection)) { 
            return true; 
        } else { 
            return false; 
        } 
    } 

    public function AffectedRows() { 
        return mysql_affected_rows($this->connection); 
    } 

    public function Open() { 
        if (is_null($this->database)) 
            die("MySQL database not selected"); 
        if (is_null($this->hostname)) 
            die("MySQL hostname not set"); 

        $this->connection = @mysql_connect($this->hostname, $this->username, $this->password); 

        if ($this->connection === false) 
        die("Could not connect to database. Check your username and password then try again.\n"); 

        if (!mysql_select_db($this->database, $this->connection)) { 
            die("Could not select database"); 
        } 
    } 

    public function Close() { 
        mysql_close($this->connection); 
        $this->connection = null; 
    } 

    public function Query($sql) { 
        if ($this->connection === false) { 
            die('No Database Connection Found.'); 
        } 

        $result = @mysql_query($sql,$this->connection); 
        if ($result === false) { 
            die(mysql_error()); 
        } 
        return $result; 
    } 

    public function FetchArray($result) { 
        if ($this->connection === false) { 
            die('No Database Connection Found.'); 
        } 
         
        $data = @mysql_fetch_array($result); 
        if (!is_array($data)) { 
            die(mysql_error()); 
        } 
        return $data; 
    } 
} 
?> 

/include/class/Sqlite.php 

<? 

class Sqlite extends Database { 

static private $instance; 

private $error; 
private $permission; 

private function __construct($dbName, $dbPerms) { 
  $this->database = $dbName; 
  $this->permission = $dbPerms; 
} 

static function getInstance($dbName=null, $dbPerms=null) { 
  if(!Sqlite::$instance) { 
   Sqlite::$instance = new Sqlite($dbName, $dbPerms); 
  } 
  return Sqlite::$instance; 
} 

public function Open() { 
  if(is_null($this->database)) { 
   die("Sqlite database not selected"); 
  } 
  if (is_null($this->permission)) { 
   die("Sqlite permissions not set"); 
  } 
  if(file_exists($this->database)) { 
   $this->connection = sqlite_open($this->database, $this->permission, $this->error); 
  } else { 
   $this->connection = sqlite_open($this->database, $this->permission, $this->error); 
   $this->Query('CREATE TABLE states (state varchar(50))'); 
   $this->Query("INSERT INTO states VALUES ('vermont')"); 
   $this->Query("INSERT INTO states VALUES ('texas')"); 
  } 

  if ($this->connection === false) { 
   die($this->error); 
  } 
} 

public function Close() { 
  sqlite_close($this->connection); 
  $this->connection = null; 
} 

public function Query($sql) { 
  if ($this->connection === false) { 
   die('No Database Connection Found.'); 
  } 
  $result = sqlite_query($this->connection, $sql); 
  if ($result === false) { 
   die($sql); 
  } 
  return $result; 
} 

public function FetchArray($result) { 
  if ($this->connection === false) { 
   die('No Database Connection Found.'); 
  } 

  $data = @sqlite_fetch_array($result); 
  if (!is_array($data)) { 
   return false; 
  } 
  return $data; 
} 

public function FetchAll($result) { 
  if ($this->connection === false) { 
   die('No Database Connection Found.'); 
  } 

  $data = @sqlite_fetch_all($result); 
  if (!is_array($data)) { 
   $this->error = 'Fetch All Failed.'; 
   return null; 
  } 
  return $data; 
} 

function table_exists($table) { 

  return sqlite_fetch_single($rez) > 0; 
} 
} 
?> 

index.php 


<? 

// the following code will make it so that the class directory is in your include_path // this allows the __autoload function to work. 
$cur = ini_get("include_path"); 
$cur .= PATH_SEPARATOR.dirname(__FILE__).'\\include\\class\\';; 
ini_set("include_path", $cur); 

// this will load any classes that are not found and are located in the // /include/class/ folder. 

function __autoload($class) { 
include($class . '.php'); 

/* Check to see it the include defined the class */  if ( !class_exists($class, false) ) { 
  trigger_error("Unable to load class $class", E_USER_ERROR);  } } 

// get an instance of the sqlite database $db = Sqlite::getInstance('mysqlitedb', 0666); $db->Open(); $result = $db->Query('SELECT * FROM states'); $arr = $db->FetchAll($result); 

echo '<pre>'; 
print_r($arr); 
echo '</pre>'; 

/* 
// this is how you would use the Mysql class 

$db1 = Mysql::getInstance('localhost', 'mydb', 'user', 'password'); $db1->Open(); $result = $db1->Query("SELECT * FROM table"); 
$arr1 = $db1->FetchArray($result); 

echo '<pre>'; 
print_r($arr1); 
echo '</pre>'; 

*/ 

?>