Upgrading PHP and Database to Version 8.2

I need a professional with profound knowledge in PHP and databases. Currently, my website operates on PHP 5.6, and I'm looking to upgrade it to version 8.2. Along with the PHP update, I require the database to be upgraded corresponding with the new PHP version. My website is built using custom PHP, not on a specific PHP framework or CMS.

Ideal Skills and Experience:
- Expertise in PHP and database management.
- Experience upgrading PHP from 5.6 to 8.2.
- Proficiency in handling custom PHP websites.

Please bid if you've the expertise for this upgrade, and can ensure the website's optimal functioning post upgrade.