I want to change detail.php?id=4 to detail/4,but my .htaccess file not working

Solution:

You're talking about using .htaccess to rewrite your URLs internally and route them appropriately to your application.

You should try with this specific .htaccess example that will do what you're looking for:

    RewriteEngine On

    # external redirect from actual URL to pretty one
    RewriteCond %{THE_REQUEST} /detail(?:\.php)?\?id=([^\s&]+) [NC]
    RewriteRule ^ detail/%1? [R=302,L,NE]
    # internal forward from pretty URL to actual one
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteRule ^detail/([^/]+)/?$ detail.php?id=$1
Copy code

EDITED:

Solution:

You are doing the opposite in your htaccess, redirecting detail/4 to detail.php?id=4. In your question you say ?id=4 to /4.

So swap, edit and test