I want to connect my Argon application with a mysql database.
Text will be selected in the database.
The application uses Vuforia and Three.js.
I’m not sure exactly how to answer this. Argon4 just uses the system webviews, so you would use any of the “usual” web methods of talking to a database. Some of that depends on how the database is set up and hosted, others depend on what server-side resources you have (e.g., are you using node.js, or PhP + apache, etc).