How can I get PHP to connect locally to MySQL? - php

Question

I'm trying to test a PHP website locally on an Ubuntu 16.04 machine, but I'm having trouble connecting to MySQL database using mysqli_connect().
I have Apache 2.4 running with mod_php7.0.
I installed the Ubuntu package php7.0-mysql.
Accessing a php.info() file at a localhost address in the same directory as the website indicates that my php.ini file is /etc/php/7.0/apache2/php.ini.
In that file, I removed the comment from the line ;extension=php_mysqli.dll.
The file I'm trying to access contains the line
$con=mysqli_connect("localhost","db_user","db_password","db_name");
When I try to access the site, I get the error
Warning: mysqli_connect(): php_network_getaddresses: getaddrinfo failed: Name or service not known"
with reference to the line above.
I have MySQL running locally with the given user, password, and database defined. I've tried using 127.0.0.1 instead of localhost, but the error is the same.
The error appears to be that PHP can't make a local connection to MySQL. How can I figure out what's wrong?
Edit To give more context, I'm trying to create a localhost version of a website that works on its production/dev servers. As far as I can tell, I've recreated all relevant aspects of the server setup, but obviously I've missed something.
The biggest difference between the local setup and production/dev version is that I have PHP7 locally but PHP5.5.9 on production/dev. My best guess at this point is that this difference is what's responsible for the localhost failure, but I don't know enough about PHP to narrow down what it might be.

Answer 1

Use the following to connect to MySQL database on localhost.
<?php
$servername = "localhost";
$username = "root";
$password = "mysql-password";
$dbname = "database-name";
$conn = mysqli_connect($servername, $username, $password,$dbname);
if (!$conn) {
die("Connection failed: " . mysqli_connect_error());
}
?>