This is a simple MySQL database handler in PHP using PDO. The default database type used is MySQL, but this can be changed by making the following changes: 1: Update the default port number on line 28. 2: Update the DSN on line 30 to reflect the database system used. 3: Change the SQL query on line 44 to the equivalent of the SQL query to select…

dbhandler.php

<?php
/**
 * @author Jorai Rijsdijk
 * @desc A simple MySQL database handler in PHP using PDO.
 * @version 1.3
 * Note: 
 *	The default database type used is MySQL, but this can be changed by making the following changes:
 *	 1: Update the default port number on line 28 (constructor).
 *	 2: Update the DSN on line 30 (new PDO object) to reflect the database system used.
 *	 3: Change the SQL query on line 44 (in the setDB function) to the equivalent of the SQL query to select a different database.
 */
Class dbHandler{
	const INTERNAL_HANDLING = 1;
	const THROW_EXCEPTION = 2;
	const IGNORE_ERRORS = 3;
	
	private $pdo = null, $stmt = null;
	private $errorHandling = self::INTERNAL_HANDLING;
	
	/**
	 * Create a new dbHandler object to interact with a database using PDO. All parameters are optional.
	 * @param string $database The database to connect to
	 * @param string $user The user to login with
	 * @param string $password The password belonging to the user
	 * @param string $server The hostname of the server to connect to
	 * @param int $port The server port for the database
	 */
	function __construct($database, $user, $password, $server = "localhost", $port = 3306){
		try{
			$this->pdo = new PDO('mysql:host='.$server.';port='.$port.';dbname='.$database.';charset=utf8',$user,$password);
			$this->pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
			$this->pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
		} catch (PDOException $e){
			$this->processException($e);
		}
	}
	
	/**
	 * Change the database to direct your queries to
	 * @param string $dbName The name of the database to connect to.
	 * @return boolean Whether or not the change succeeded. Error handling will be applied according to the settings.
	 */
	public function setDB($dbName){
		return ($this->query("USE ?", array($dbName)))?true:false;
	}
	
	/**
	 * Process a query and get the PDOStatement object back
	 * @param string $query The query to process. Use :paramname for named parameters and ? for anonymous parameters.
	 * @param array $params The parameters array, just like you would use with PDO
	 * @return PDOStatement|boolean The PDOStatement object retreived from the database or false if something failed.
	 */
	public function query($query, array $params = array()){
		try{
			if($this->pdo !== null){
				if(($this->stmt = $this->pdo->prepare($query))!==false){
					if($this->stmt->execute($params))
						return $this->stmt;
				}
			}
			return false;
		} catch (PDOException $e){
			$this->processException($e);
		}
	}
	
	/**
	 * Get the latest insert id for an auto_increment column
	 * @return int The Latest insert id of an auto_increment column
	 */
	public function lastInsertId($name = NULL){
		return $this->pdo->lastInsertId($name);
	}
	
	/**
	 * Set the errorHandling method to either INTERNAL_HANDLING, THROW_EXCEPTION or IGNORE_ERRORS
	 * @param int $handlingMethod The handling method preferred
	 */
	public function setErrorHandling($handlingMethod){
		switch($handlingMethod){
			case self::INTERNAL_HANDLING:
			case self::THROW_EXCEPTION:
			case self::IGNORE_ERRORS:
				$this->errorHandling = $handlingMethod;
			default:
		}
	}
	
	/**
	 * This private method processes exceptions based on the errorHandling settings
	 * @param PDOException $e The exception to process
	 * @throws PDOException Only if errorHandling is set to dbHandler::THROW_EXCEPTION
	 */
	private function processException(PDOException &$e){
		switch($this->errorHandling){
			case self::INTERNAL_HANDLING:
				self::handleException($e);
				break;
			case self::THROW_EXCEPTION:
				throw $e;
				break;
			default:
		}
	}
	
	/**
	 * Handle a PDOException by showing the stacktrace properly and dieing.
	 * @param PDOException $e The exception to handle
	 */
	public static function handleException(PDOException &$e){
		$trace = $e->getTrace();
		$msg = "<span class='error'><b>An error has occured: </b><br><pre>";
		$msg .= $e->getMessage() . '<br>';
		foreach($trace as $line){
			$msg .= "\t<b>at</b> ";
			if(!empty($line['class'])){
				$msg .= $line['class'];
				$msg .= $line['type'];
			}
			$msg .= $line['function'] . '()';
			$msg .= " <b>in</b> " . self::trimFilePath($line['file']) . " (<b>line</b> " . $line['line'] . ")<br>";
		}
		$msg .= '</pre></span>';
		die($msg);
	}
	
	/**
	 * Trim the file path to start at the Document_Root
	 * @param string $path The path to trim
	 * @return string The trimmed path
	 */
    	private static function trimFilePath($path){
        	return str_replace($_SERVER['DOCUMENT_ROOT'], "", $path, $count);
    	}
}
?>