The configuration that needs to be modified when switching between high and low versions of MySQL 5-8 (take aicode as an example here)

An error is reported due to the conflict between the version of the database at the initial startup ：

WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

My local environment is 8.0 Of MYsql Therefore, the configuration of the database is modified to 8.0

   <mysql-connector-java.version>8.0.21</mysql-connector-java.version>
   <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>${mysql-connector-java.version}</version>
            </dependency>

perhaps

 <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>8.0.21</version>
            </dependency>

After the modification
Restart error ：

Loading class com.mysql.jdbc.Driver'. This is deprecated. The new driver class iscom.mysql.cj.jdbc.Driver’. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.

hold com.mysql.jdbc.Driver modify com.mysql.cj.jdbc.Driver

We make the following changes
Join this

driver-class-name: com.mysql.cj.jdbc.Driver

Could not create connection to database server. Attempted reconnect 3 times. Giving up.

1、 Will all driver-class-name Values are from com.mysql.jdbc.Driver It is amended as follows com.mysql.cj.jdbc.Driver（ It said that ）

2、 stay url Add a time zone parameter after the parameter of ：&serverTimezone=UTC

3、 modify url The value in the connection parameter is updated to ：zeroDateTimeBehavior=CONVERT_TO_NULL

spring:
  profiles: dev
  datasource:
      #url: jdbc:mysql://localhost:3306/easycode?autoReconnect=true&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull
      url: jdbc:mysql://localhost:3306/easycode?autoReconnect=true&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=CONVERT_TO_NULL&serverTimezone=UTC
      username: root
      password: root
      filters: log4j,wall,mergeStat
      driver-class-name: com.mysql.cj.jdbc.Driver

Annotated is the previous ; New is modified ;

I hope I can help you ;