Cloud 9 IDE can't connect to database - php

Question

I have tried a number of things to connect to my database in cloud 9 but I keep getting similar errors.
This is my PHP code:
<?php
// Create connection
$con=mysqli_connect($IP, "$C9_USER", "", "c9");
//(host,username,password,dbname)<- guide for me
// Check connection
if (mysqli_connect_errno()) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
?>
I took the basic code from w3schools and I used it with a document explaining how cloud 9's mysql database works: https://docs.c9.io/setting_up_mysql.html
But I can't seem to connect without getting the follow error:
Failed to connect to MySQL: Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
So I'm wondering if there's a different way to change the socket to the address that cloud 9 recommended: Note: MySQL socket file can be found in ~/lib/mysql/socket/mysql.sock

Answer 1

Credit to Loz Cherone
When using Cloud 9 IDE, the php variables $ID and $C9_USER mentioned in this article are not defined.
In order to retrieve these variables for use in your code, you must use the cloud 9 ide terminal by pressing ALT + T and entering:
echo $ID
echo $C9_USER
Then take those values and place them in a variable in your php code like so:
<?php
// Create connection
$IP = "value from terminal";
$C9_USER = "value from terminal";
$con=mysqli_connect($IP, $C9_USER, "", "c9");
//mysqli_connect(host,username,password,dbname); << guideline
// Check connection
if (mysqli_connect_errno()) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
?>
SIDE NOTE: Make sure when running the mysql code that you have the data base turned on. You can turn it on by typing mysql-ctl start in the terminal.