Should I add a "MySQL_URI" to the MySQL Kubernetes deployment file?

This is a Kubernetes deployment file that originally was using only MongoDB database. I tried to add MySQL to it as well like below:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: auth-depl
spec:
  replicas: 1
  selector:
    matchLabels:
      app: auth
  template:
    metadata:
      labels:
        app: auth
    spec:
      containers:
        - name: auth
          image: learner/auth
          env:
            - name: MONGO_URI
              value: 'mongodb://auth-mongo-srv:27017/auth'
            - name: JWT_KEY
              valueFrom:
                secretKeyRef:
                  name: jwt-secret
                  key: JWT_KEY
            - name: MYSQL_ROOT_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: mysql-secret
                  key: MYSQL_KEY
---
apiVersion: v1
kind: Service
metadata:
  name: auth-srv
spec:
  selector:
    app: auth
  ports:
    - name: auth
      protocol: TCP
      port: 3000
      targetPort: 3000

But I am not sure if I must also define another env for MYSQL_URI or not? Something like:

    - name: MYSQL_URI
      value: 'mysql://auth-mongo-srv:3306/auth'

It is not required to create a separate env variable for MYSQL_URI in the yaml files while encrypting the username and password for your mysql database. However, when you are referring to this DB in your application code you need to use the MYSQL_URI and this encrypted data for connecting to Mysql DB.

Please go through this link for yaml file reference.