Q:

Windows IIS - PHP PDO Mysql Could not find driver

I have the following code to connect to a Mysql database from my local PHP (Windows, using IIS),
$dbhost     = "xxxx.database.windows.net";
$dbname     = "yyyy";
$dbuser     = "uuuu";
$dbpass     = "pppp";
$driver     = "sqlsrv";
$connection = new PDO("$driver:host=$dbhost;dbname=$dbname",$dbuser,$dbpass);

php info says this:
Loaded Configuration File   C:\Program Files (x86)\IIS Express\PHP\v5.6\php.ini

I have the following in this php.ini file
[WebPIChanges]
error_log=C:\Windows\temp\PHP56ForIISExpress_errors.log
upload_tmp_dir=C:\Windows\temp
session.save_path=C:\Windows\temp
cgi.force_redirect=0
cgi.fix_pathinfo=1
fastcgi.impersonate=1
fastcgi.logging=0
max_execution_time=300
date.timezone=Europe/Minsk
extension_dir="C:\Program Files (x86)\iis express\PHP\v5.6\ext\"

[ExtensionList]
extension=php_mysql.dll
extension=php_mysqli.dll
extension=php_mbstring.dll
extension=php_gd2.dll
extension=php_gettext.dll
extension=php_curl.dll
extension=php_exif.dll
extension=php_xmlrpc.dll
extension=php_openssl.dll
extension=php_soap.dll
extension=php_pdo_mysql.dll
extension=php_pdo_sqlite.dll
extension=php_imap.dll
extension=php_tidy.dll
extension=php_sqlsrv.dll

This file exists: C:\Program Files (x86)\IIS Express\PHP\v5.6\ext\php_pdo_mysql.dll
Why do I get a "could not find driver" error? My application pool can run 32-bit or 64-bit.

A:

Two things were wrong. I had the wrong connection string. Should have been 
$connection = new PDO("$driver:Server=$dbhost;Database=$dbname",$dbuser,$dbpass);

I was also missing the extension for sql server!!!
extension=php_pdo_sqlsrv_56_nts.dll

I didn't even have version 5.6 on my PC had to download it from here:
https://www.microsoft.com/en-us/download/confirmation.aspx?id=20098

