Node.js App and MySQL Deployment Fix

My Node.js application and MySQL database deployed on Vercel are facing communication and connection issues. The app operates smoothly in my local environment, but post-deployment, the frontend and backend seem to be out of sync. I'm receiving MySQL errors such as:

- #1046 (No database selected): This indicates that my application isn't selecting the database properly during runtime.
- #1044 (Access denied): This points towards potential permission issues with my MySQL database.

I require assistance in troubleshooting these MySQL connection issues, ensuring all necessary database permissions are granted, and resolving any deployment-related complications to facilitate smooth operation of my app in the live environment.

Ideal Skills and Experience:
- Extensive experience with Node.js applications and MySQL databases
- Proficiency in deploying applications on Vercel
- Strong troubleshooting skills for connection and permission issues
- Familiarity with configuring environment variables for database connections
- Ability to interpret and resolve MySQL error messages