JDBC 连接 MySQL 报错 Unknown system variable ‘query_cache_size‘

官方说法：

The query cache is deprecated as of MySQL 5.7.20, 
and is removed in MySQL 8.0. Deprecation includes query_cache_size.

query cache 在MySQL 5.7.20 已经过时了，并且在MySQL 8.0 版本中被移除了。

所以要更新mysql驱动版本

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.11</version>
</dependency>

注意8+版本配置

spring:
  datasource: # 数据源的相关配置
    driver-class-name: com.mysql.cj.jdbc.Driver #从com.mysql.jdbc.Driver修改为com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/shop?useSSL=false&useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&serverTimezone=UTC