Time to upgrade old PHP/MySQL database built on WebAssist tools

Can you be more specific about what needs changing?  I ask only because I use WebAssist's MySQLi (improved) extension which performs just fine on a modern server.  If you're using MySQLi connections, you shouldn't be having problems on that side of it. 

You say you have used WebAssist tools to build your website in the past, maybe 5+ years ago?

I don't know when WebAssist brought out their mysqli [note the (i)] database connection/query extension which is the workflow you need to deploy now for modern websites, not the old mysql [without the (i)].

Check out what version of the database connection/query extention from WebAssist you have - mysqli has been around for a long time now.

If its not the current mysqli extension then the options you have are:

1) Purchase the mysqli extention from WebAssist which still works with Dreamweaver (obviously check this before you buy)

2) Write your own connection and database queries - there are numerous php/mysqli tutorials if you search Google and Youtube

DW dropped their built in server behaviours because they were past their sell-by-date, being mysql, threatened to update them and so far never have. That's when DW dropped the ball and its now dead in the water and wont recover until they bring something innovative back to the software again which is not likely to happen. Infact its more likely to be EOLed.

Webassist MySQLi extensions will be easier to learn, espescially if you've worked with the old Dreamweaver Server behaviors before.

DMXZone server side extensions have a steeper learning curve IMO.

Manually writing the connection scripts might be a bit painful for someone so removed from working with code.

However, while DW doesn't have any built-in options for connecting to databases, WebAssist and DMX Zone still make paid extensions to do what the database panel used to (with modernized, secure code methods).

Unfortunately they aren't available on Adobe's failed extensions/add-ons marketplace and just need to be purchsed directly from the developers, like most decent DW extensions.