php - Fatal error: Class 'MySQLi' not found

I found a solution for this problem after a long analysing
procedure.
After properly testing my php installation with the command line
features I found out that the php is working well and could work with the mysql
database. Btw. you can run code-files with php code with the command php -f
filename.php
So I realized, it must something be wrong with the Apache. />I made a file with just the phpinfo() function inside.
Here I saw, that
in the line
Loaded Configuration File />my config file was not loaded, instead there was mentioned
(none).

Finally I found within the Apache configuration the
entry
/>PHPINIDir "C:/xampp/php" /> />

But I've installed the PHP 7 and so the
Apache could not load the php.ini file because there was no entry for that.
I
added

            php7_module>
 PHPINIDir
            "C:/xampp/php"

and
after restart Apache all works well.

These code
blocks above I found in my httpd-xampp.conf file. May it is somewhere else at your
configuration.
In the same file I had changed before the settings for the php
7 as replacement for the php 5
version.

#
# PHP-Module
            setup
#

#LoadFile
            "C:/xampp/php/php5ts.dll"
#LoadModule php5_module
            "C:/xampp/php/php5apache2_4.dll"
LoadFile
            "C:/xampp/php/php7ts.dll"
LoadModule php7_module
            "C:/xampp/php/php7apache2_4.dll"

As
you can see I've the xampp package installed but this problem was just on the Apache
side.

So I hope it helps someone to fix this
problem.