用PHP到Access数据库文件的连接字符串是什么

<?php
// Microsoft SQL Server using the SQL Native Client 10.0 ODBC Driver - allows connection to SQL 7, 2000, 2005 and 2008
$connection = odbc_connect(\"Driver={SQL Server Native Client 10.0};Server=$server;Database=$database;\", $user, $password);

// Microsoft Access
$connection = odbc_connect(\"Driver={Microsoft Access Driver (*.mdb)};Dbq=$mdbFilename\", $user, $password);

// Microsoft Excel
$excelFile = realpath(\'C:/ExcelData.xls\');
$excelDir = dirname($excelFile);
$connection = odbc_connect(\"Driver={Microsoft Excel Driver (*.xls)};DriverId=790;Dbq=$excelFile;DefaultDir=$excelDir\" , \'\', \'\');
?>

$dsn=\'database.accdb\';
$username=\'\';
$password=\'\';
$connect=odbc_connect($dsn, $username, $password);

<?php

$db = $_SERVER[\"DOCUMENT_ROOT\"] .\"/AccessDatabase/reg.accdb\"; //AccessDatabase is folder in htdocs where the database is store 
if (!file_exists($db))
{
       die(\"No database file.\");
}

$dbNew = new PDO(\"odbc:DRIVER={Microsoft Access Driver (*.mdb, *.accdb)}; DBQ=$db; Uid=; Pwd=;\");
$sql = \"select * from reg\"; //reg is table name
$rs = $dbNew->query($sql);

while($result = $rs->fetch())
{
     echo $result[0].\": \".$result[1].\": \".$result[2].\"<br />\";
} 


?>