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>
java.sql.SQLException: Unknown system variable 'query_cache_size'
原文：https://www.cnblogs.com/jack-zhou21235/p/12191870.html