The application.properties file is used to connect the database with the application and define how the database will behave. Here is the code for application.properties:

# ===============================
# DATABASE
# ===============================

spring.datasource.url=jdbc:mysql://localhost:3306/my_app_schema?useSSL=false&allowPublicKeyRetrieval=true
spring.datasource.username=root
spring.datasource.password=12345678

# ===============================
# JPA / HIBERNATE
# ===============================
spring.jpa.show-sql=true

# Hibernate ddl auto (create, create-drop, validate, update)
spring.jpa.hibernate.ddl-auto = update

## Hibernate Properties
# The SQL dialect makes Hibernate generate better SQL for the chosen database
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect

Here we have used the database named my_app, and the schema is my_app_schema. We disable useSSL with useSSL=false, and to retrieve the public key we use allowPublicKeyRetrieval=true.

Here, we use spring.jpa.hibernate.ddl-auto = update, which means after restarting your server the data won't be lost.