[PHP]PDO Exception

在使用PDO時，catch Exception有兩種用法

//資料庫連線失敗
try {
	$dsn = "mysql:host=localhost;dbname=eaaaaa";
	$db = new PDO($dsn,"aaaaaa","aaaa");
}
catch (PDOException $e) {
	echo $e->getMessage();
} 

//query失敗時可以利用errorCode()和errorInfo()來做例外處理，如果query沒有出錯，errorCode()會是00000
try{
	$sql = "SELECT * FROM aaa";
	$sth = $db -> query($sql);
	if( $db -> errorCode() != '00000')
	{
		$error = $db -> errorInfo();
		throw new PDOException($error[0]. " " .$error[1]. " " .$error[2]);
	}
}catch(PDOException $e){
	print_r($e -> getMessage());
}