Include or Header PHP

[JamesU2005]

Very basic question but, when would one use the following:

header("location: destination_url.php");

over

include "destination_url.php";

Is a header safer over include, in terms of POST values.

Thanks,

James

 

[JamesU2005]

Im developing user registration in php.

There are checks in place that looks to see if a username already exists, if so then so far I have

die include(something.php)

Is this the right way or should it be header?

 

[JamesU2005]

Here is what I have:

$userexist = mysql_query("mysql query here");

$username_exist = mysql_num_rows($userexist);

if($username_exist > 0){ 
die(include "regerrorusername.php");
}

If a user does not exist the rest of the code (not shown) is run, such as checking whether the email is a valid email address, check two passwords are the same etc.

Is the include suitable?

 

[JamesU2005]

Perhaps I've got the wrong understanding of the Die function, thought it would just terminate and thus stopping anything else from running.

And before the pre-optimization police come sniffing around I have the MySQL real escape and string replace for whitespace.

Edit: Just need something to remove all Characters other than numbers or letters.

 

[JamesU2005]

The

die(include "something.php");

works fine as intended. Should I replace with something else though?