未捕获的PDOException：找不到驱动程序

Question

I have just installed an Ubuntu Server 16.04 with Nginx, and i have installed php in this way:

sudo apt-get install php7.0-cli php7.0-cgi php7.0-fpm php7.0-curl

And for MySql i have installed percona, in this way:

apt-get install percona-server-server-5.7 percona-server-client-5.7

but I can't understand why i can't use PDO in my php script, this is my code:

$db = new PDO("mysql:dbname=db;host=localhost;charset=utf8", "username", "password");

I get this error:

Uncaught PDOException: could not find driver

I have searched online and I have found that i have to uncomment this line in Windows in php.ini:

;extension=php_pdo_mysql.dll

or this line on Linux:

;extension=php_pdo_mysql.so

I have checked my php.ini in:

/etc/php/7.0/fpm/php.ini

and i have a .dll file and not a .so file, I can't also understand why I have a dll instead of a so. Anyway enabling that .dll file and restarting php nothing change. Anyone can help me?

Thanks

Answer 1

Installing the mysql client/server packages doesn't effect PHP. PHP still needs the bindings to talk to your mysql server, specifically in your case the PDO mysql driver.

The package is probably going to be called php7.0-pdo-mysql depending on which repositories are configured your Ubuntu package manager. If you're using PHP 7 on Ubuntu 16.04 it's more than likely going to be a meta package that includes php7.0-mysql. Here's what I got from aptitude on 16.04 using the Ondrej PPA.

aptitude show php7.0-pdo-mysql

Package: php7.0-mysql                    
State: installed
Automatically installed: no
Version: 7.0.9-1+deb.sury.org~trusty+1
Priority: optional
Section: php
Maintainer: Debian PHP Maintainers 
Architecture: amd64
Uncompressed Size: 514 k
Depends: php-common (>= 1:35), ucf, php7.0-common, libc6 (>= 2.15)
Provides: php-mysqli, php-mysqlnd, php-pdo-mysql, php7.0-mysqli, php7.0-mysqlnd, php7.0-pdo-mysql
Description: MySQL module for PHP
 This package provides the MySQL module(s) for PHP. 

The php7.0-pdo-mysql is the one we're interested in for loading the mysql driver for PDO in PHP. So make sure to search your package manager to find the correct package before you attempt installing, but there should be a similar package for your distro/repositories.

Once installed you'll need to restart php-fpm, something like sudo service php7.0-fpm restart and then check your phpinfo() to make sure the pdo_mysql driver is now loaded.

You shouldn't need to edit your php.ini manually when installing through your package manager. Also, adding the extension=pdo_mysql.so line to your php.ini has no effect if the extension doesn't exist. And obviously, trying to load dll won't work on linux, those are Windows-only libraries.