java.sql.SQLException: Unknown system variable 'query_cache_size'

Jar包版本不对：

<dependency>
       <groupId>mysql</groupId>
       <artifactId>mysql-connector-java</artifactId>
       <version>5.1.40</version> 
</dependency>

换个版本就好了：

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