I would start by defining installed php modules. This can be done using
php -m
"phpX.Y-mysql", , php . ( X.Y php.
, , , :
sudo apt-cache search php-mysql
:
sudo apt-cache search php-mysql
php-mysql - MySQL module for PHP [default]
php7.0-mysql - MySQL module for PHP
php5.6-mysql - MySQL module for PHP
php-mysqlnd-ms - MySQL replication and load balancing module for PHP
php7.1-mysql - MySQL module for PHP
php- . :
sudo apt-get install php7.1-mysql