Q:

PHP + odbc: Data source name not found and no default driver specified

I use odbc driver to load data from an MS Access database file.
PHP code:
$connStr ='odbc:Driver={Microsoft Access Driver (*.mdb, *.accdb)};' . 'Dbq=C:\\inetpub\\wwwroot\\dir\\dir.accdb;';

$dbh = new PDO($connStr);

$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$sql="my_sql_query";
$sth = $dbh->prepare($sql);
$params=array();
$sth->execute($params);

In a local computer this works, but when I uploaded to the main server, I get this message when trying to access site:
Error:

PHP Fatal error: Uncaught exception 'PDOException' with message
  'SQLSTATE[IM002] SQLDriverConnect: 0 [Microsoft][ODBC Driver Manager]
  Data source name not found and no default driver specified' in
  C:\inetpub\wwwroot\dir\index.php:424 Stack trace: #0
  C:\inetpub\wwwroot\dir\index.php(424):
  PDO->__construct('odbc:Driver={Mi...') #1 {main} thrown in
  C:\inetpub\wwwroot\dir\index.php on line 424

System:

PHP Version: 5.6.3
Server: Windows Server 2008 R2 with IIS 7.5

I have installed 64bit ODBC Driver 11 for SQL Server and extensions are enabled in php.ini file. I saw a few tutorials indicating that I have to open ODBC Data Source Administrator, go to System DSN tab, and create a System Data Source. If i have to do this, at Server to connect what should I select, because I am actually using this driver for accessing an Access database file. Also in test environment, I didn't have to do something like this.
Any ideas?
Thank you in advance
EDIT
OK. I did the following: 
1) I installed MS Visual C++ 2015 because i was missing a dll file for Microsoft Access Database engine 2016(This adds the driver missing in ODBC).
2) Installed MS Access Database engine 2016.
3) After those 2 installations i created a DSN and pointing it to my access file 
When i try to run the php file i get this: 
PHP Fatal error:  Uncaught exception 'PDOException' with message 'SQLSTATE[HY009]:                                                                          
Invalid use of null pointer: 0 [Microsoft][ODBC Microsoft Access Driver]Invalid use of null pointer  (SQLPrepare[0] at ext\pdo_odbc\odbc_driver.c:206)' in C:\inetpub\wwwroot\dir\index.php:434
Stack trace:
#0 C:\inetpub\wwwroot\dir\index.php(434): PDO->prepare('')
#1 {main}
  thrown in C:\inetpub\wwwroot\dir\index.php on line 434 

Any ideas??

A:

You need to specify the correct ODBC driver in the connection string.
If your PHP works in 32-bit mode - you have to use 32b drivers.
Second, drivers for SQL Server and drivers for MS Access are two very different things. If you need to work with .MDB - you need to install MS Access.
Creating System DSN in Data Source Administrator can be useful, it greatly simplify the connection string in your program (to the point of "DSN=mydsn" and nothing else). It also allows you configure the DSN (choose a different version of the driver, change location of the file, etc) in a convenient way. It also allows you to connect to the same database from different applications by simply: "DSN=mydsn".
The only case when creating DSN could be disadvantageous is if you, by some reason, cannot create the DSN. For example if you do not have enough permissions on the machine. But in all other cases - create the DSN, it will save a lot of time and effort.

