Conectar proyecto Spring Boot con MySql y PostgreSQL

Configurar la Conexión a la Base de datos:

# MySQL connection settings
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/testdb?serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=secret

# JPA settings

spring.jpa.hibernate.ddl-auto=update

spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQLDialect

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# Postgresql connection settings

spring.datasource.driver-class-name=org.postgresql.Driver

spring.datasource.url=jdbc:postgresql://localhost/testdb

spring.datasource.username=postgres

spring.datasource.password=secret

# JPA settings

spring.jpa.database=postgresql

spring.jpa.hibernate.ddl-auto=update

spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect

Opcional:

spring.jpa.show-sql=true

spring.jpa.properties.hibernate.format_sql=true