What is permalink?
permalink definition on a wiki website:
A permalink, or permanent link, is a URL that points to a specific blog or forum entry after it has passed from the front page to the archives. Because a permalink remains unchanged indefinitely, it is less susceptible to link rot. Most modern weblogging and content-syndication software systems support such links. Other types of websites use the term permanent links, but the term permalink is most common within the blogosphere. Permalink is a portmanteau word made from permanent link. Permalinks are often simply stated so as to be human-readable.
How’s the shape of permalink structure?
Generally, dynamic page’s url will look like this:
http://www.example.com/index.php?page=10
become:
http://www.example.com/what-is-permalink,10.html
If we see the appearance of the second link, as if, what-is-permalink,10.html file exist in the server, whereas, in reality there is no such a file. there is no fixed rule in the composition of the permalink, just do not use a space as a link, instead we can use the underscore sign (_) or a minus sign (-) or dots (.) or coma (,), as in the example above, which used a minus sign (-) and coma (,).
How to apply the permalink structure like in the example above?
As we know, nginx support rewrite directive.
if (!-e $request_filename) {
rewrite ^/(.*),([0-9]+).html$ /index.php?page=$2 last;
break;
}
In the php code:
<?php
$id = $_REQUEST[page];
// make sure value of $id only contain numeric
if (is_numeric($id))
{
$query = "SELECT page_content FROM page_table WHERE page_id`='$id'";
...
...
} else {
echo "404 page";
}
?>
Get value from uri paramater called page, pass it to variable called $id, used for sql query.
Of course, the example I described above is only a very simple example of how permalink made?. compared with the permalink in wordpress or joomla cms that uses a complex system permalink, the example above only very very basic principles of a permalink.