Save php code in database

Saving PHP code in database commonly is a bad practice:
- after get a record from DB you have to parse all PHP codes and use eval() to execute those. It's a direct way to get XSS/SQL-injection.
- you end up with non transparent code that is difficult to debug when looking for errors.

Use relative URLs as was advised above. Never use hardcoded absolute URs with domain name specified. Otherwice you'll get a headache in case of use preffix like www. or subdomains m. for mobile version (and with http:/https too).