通过从URL获取user_name来使用PHP和MYSQL创建用户页面：user / username

I am using PHP header redirect to redirect users from account/?id=$id to user/$username

Successfully it takes for instance account/?id=1 to user/samuel as long as the user exists. Now, this page user/samuel is quite empty ( 404 ).

How do I make it return the user data in the user/samuel using something like isset($_GET[]) manual? in addition of course to adding MYSQL query to retrieve data for the user which has username extracted from the URL, and get their data from database table. and I will be placing all the code in user/index.php

As long as I could make account/?id=$id get the $id from URL ( parameter ) and do other db stuff I think it is also possible to get $username from the URL.. even though user/?username could do it but I don't want to include an ? in the URL..

Any thoughts?

It might be better if you use Url Rewriting (aka friendly urls)

You can see this link which answers this same question, although your case is a little bit different. Apache friendly urls

Since you can't convert $id to $username (both are different values) I would recommend to change the link to 'user/ID' instead of 'user/USERNAME'.

This is a pretty broad topic, what you need to do is parse the url - IE break it into parts and then match the url to a set of actions. This is commonly known as routing.

A naive implementation would be a:

$parts = explode($_SERVER['REQUEST_URI'], '/');

if ( $parts[-2] === 'user' && $parts[-1] ) {
   $stmt = $pdo->prepare("SELECT * FROM 'users' WHERE username = ? OR id = ?");
   $result = $stmt->execute(array($parts[-1], array($parts[-1]));
   // ... do something if the user is found or not.
}

But this would fail if the url contains query parameters (?foo=bar) or a hash (#foo).

Instead you can use parse_url to make sure you only use the path.

$path = parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH);
$parts = null;

// Match the url with a regular expression.
preg_match(/^\/user\/(\w*)$/, $path, $parts);

if ( count($parts) == 2 ) {
   $stmt = $pdo->prepare("SELECT * FROM 'users' WHERE username = ? OR id = ?");
   $result = $stmt->execute(array($parts[-1], array($parts[-1]));
   // ... do something if the user is found or not.
}

But in the end you might want consider using a micro framework such as Silex, Slim or using the Routing component from Symfony2 so that you can concentrate on building your application rather than reinventing the wheel.