MySQL connect function runs even if the username is wrong - php

Question

I already know that if you want to connect to a database using MySQL you have to provide the correct URL, username, password that is the normal thing here is my code:
<?php
$mysql_id = mysql_connect('localhost', 'root', '');
mysql_select_db('Booklet', $mysql_id);
if(!$mysql_id)
{
echo"cannot connect to database ";
}
?>
This code runs well, however if I messed with the username which is root it still connects here is the code:
<?php
$mysql_id = mysql_connect('localhost', 'rot', '');
mysql_select_db('Booklet', $mysql_id);
if(!$mysql_id)
{
echo"cannot connect to database ";
}
?>
Can anyone explain to me why is this happening?

Answer 1

As of PHP 5.5.0 mysql_* functions are deprecated and you should not code with thoses. Think of thoses function as a crawling zombie, you don't go and kiss it, do you ?
You should use MySQLi or PDO for doing operations on database. Please don't bother with mysql_* anymore, you dont want that. It's like asking to code on Windows Milenium, hell, even booting this thing is a nightmare.
Anyway, to answer the question you should write :
$mysql_id = mysql_connect('localhost', 'rot', '') or die(mysql_error());
Or better, you should look at the doc of MySqli and be free of thoses shackles. Think about that, please.

Answer 2

You never bothered checking for failure. Your code simply assumes success and blunders onwards.
$mysql_id = mysql_connect('localhost', 'rot', '') or die(mysql_error());
^^^^^^^^^^^^^^^^^^^^^^
mysql_select_db('Booklet', $mysql_id) or die(mysql_error());
All of the mysql_*() function return boolean false on failure. You need to check for that false. Never ever assume a DB operation succeeded. Always assume failure, check for that failure, and treat success as a pleasant surprise.

Answer 3

This extension is deprecated as of PHP 5.5.0, and will be removed in the future. Instead, the MySQLi or PDO_MySQL extension should be used.
try to debug your code by adding mysql_error() like this
$mysql_id = mysql_connect('localhost', 'rot', '');
mysql_select_db('Booklet', $mysql_id);
echo " debug return: " . mysql_error();
or simply update your code if you have a newest version of php > 5.5.0
$mysql_id = mysqli_connect("myhost","myuser","mypassw","mybd") or die("Error " . mysqli_error($link));

Answer 4

Using the new MySQLi functions, you would get a false back on trying to connect, also you can pass you database as fourth parameter. So your code could look like this:
<?php
if($mysql_id = mysqli_connect('localhost', 'root', '', 'Booklet'))
{
/* do something like mysqli_query($mysql_id, ... */
}
else
{
echo"cannot connect to database ";
}
?>