I recommend watching this playlist: Node-RED Essentials. The videos are done by the developers of node-red. They're nice & short and to the point. You will understand a whole lot more in about 1 hour. A small investment for a lot of gain.
Why would you think that? What other single node have you found that does everything that another software program does? You could build your own implementation of phpMyAdmin but you would need many nodes to do it.
As @jbudd noted, you could create a small flow to open phpMyAdmin in the dashboard but no single node will do it.
No because a database is more than just CRUD, where should it start and end ? There are better tools available, which are dedicated and better for this task. I use SequelPro (on mac), phpmyadmin is a nice alternative too, there are so many. Creating this in node-red will be a project without an end.
While the idea of a Node-RED version of phpMyAdmin is interesting, it isn't really the focus of Node-RED.
Now a real equivalent would be a standalone Node.JS version nodeMyAdmin perhaps!.
This is because, phpMyAdmin is really a stand-alone application. The node.js equivalent doesn't NEED the integration that Node-RED brings, all it needs to do is to create a web interface along with all of the dedicated tasks that any MyAdmin tool needs.
If you search, maybe such a thing already exists? If not, you could make a bit of a name for yourself by creating it. All you need is node.js along with ExpressJS and a bunch of code.