It looks like you might be using a standard MySQL connection on a PHP7 site. You would need to use a MySQLi connection to work with PHP7.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.