I struggled with this for a day when I suddenly got this error on my local xampp server. After finding out bits and pieces from various forums here is how I fixed it.
First I made a back-up of my xampp folder.
Then I went into the xampp folder, non back-up folder, and renamed the php folder to php-old
Then I installed xampp over top (it did keep all my files and databases so I did not lose them, no promises though so thus the back-up folder in step one.)
Up and running with no errors.
The apparent conflict is somewhere in the php file. Option #2 is to download a new version of PHP and copy the files directly over the php files. I can't really comment on it though as I have not tested it. Just an option if you are more comfortable doing that
the version of joomla is v3.3.3
the file configuration.php doesn't contains "public $dbtype = 'mysqli'"
what should I do?
the problem still exist
Open configuration.php and change this line:
public $dbtype = 'mysqli';
public $dbtype = 'mysql';
thanks to this site:http://www.maxofweb.com/2013/02/solve-database-connection-error-1-mysql.html#.ucx8m70uvf8