Making a Connection

With SQLite, you could jump right an and create a database but with MySQL, you must first connect to the database server. That is done with the function mysql_connect(). mysql_connect() has three required arguments: host, user name and password; three optional arguments; database name, port and socket and returns a variable that will be used in subsquent database interactions or FALSE if it fails for any reason.

Host:

This will usually be "localhost" but it may be the host name or IP.

User name

Unless you have set a diffrent username/password for a particular database, this will be user name that you use to log into cPanel

Password

Unless you have set a diffrent username/password for a particular database, this will be password that you use to log into cPanel

Database name (optional)

Use when logging into a particular database.

Port (optional)

Socket (optional)

When you use mysql it will look something like this:


<? 
@$connection = mysql_connect("localhost", "user_name", "password") or die("Failure message."); ?>

Note that the function is preceded by an error supression operator. For security reasons, when you finish your scripts, they should reveal as little about the database as possible and a PHP error message may reveal too much. When you are working on the script, you may omit the error supresser but include it when your script is finished and use die to display your own error message when mysql_connect() returns false.

Disconnecting

Disconnecting from the database when you are done with it is not required but it is good form. Disconnecting from the database is done with the function mysql_close() which has one argument; the variable created when you used mysql_connect(). To close the example above:


<? 
mysql_close(); 
?>

The next example combines the two. The script will make a connection, tell you if you succeeded (or filed), then break the connection

Example as .txt


<?php
$user = "your user name";
$pass = "your password";

$link = mysql_connect("localhost", "$user", "$pass" );
/* check connection */
if (!$link) {
    printf("Connect failed: %s\n", mysql_connect_error());
    exit();
}
else { 
printf("Host information: %s\n", mysql_get_host_info($link));
}

/* close connection */
mysql_close($link);
?>

Warning

Exposing the password to your cPanel is just about the worst thing you can possibly do. Any script you have that can expose source code and accepts a file path may expose your password. If you have such a script, you should either password protect it or modify it so that regular experessions only allows full URL's.

If the script is public you may want to create an additional layer of security by storing the username and password as variables on a PHP file in a directory that is not accessable to browsers and including it in your MySQL script. You can't do this if you are using one of the WebTV friendly file managers. You must use cPanel's file manager.

When you use cPanel's file manager, you'll see a directory named public_html. All of your public accessible files are in that directory. None of the contents of any other directory is accessible to a browser. Create a directory to put your login script. Make a login script like this ...


<?php
function connect()
{
$user = "your user name";
$pass = "your password";
$link = mysql_connect( "localhost", "$user", "$pass" );
return $link;
}
?>

Text

The login script is a function that returns a MySQL resource. Include that file wherever you need to connect to MySQL


<?
$file = "../../../../../secret/abracadrabra.php";
include("$file");

if ( @!$link = connect() )
 {
  echo "Connection to MySQL failed<br>";
  printf("Connect failed: %s\n", mysql_connect_error());
  exit;
 }

echo "Connected to MySQL<br>";
printf("Host information: %s\n", mysql_get_host_info($link));
mysql_close($link);
?>

Text

DJ Mike's Tutorials: PHP and MySQL

Making a Connection

Disconnecting

Warning