Record the problems encountered in the learning process of Java mybatis framework

1. An exception occurred while building the first mybatis project:

Exception in thread "main" org.apache.ibatis.exceptions.PersistenceException: 

Error querying database. Cause: java.sql.SQLException: Error setting driver on UnpooledDataSource. 
Cause: java.lang.ClassNotFoundException: Cannot find class: com.mysql.cj.jdbc.Driver

Solution: the MySQL connector Java driver version is used incorrectly
I use MySQL version 8.0.22

import the driver of version 5.1.23, and the dependency declared in pom.xml file is

<dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.23</version>
    </dependency>

The two versions do not correspond, so the driver error cannot be found.
the solution is to download the driver of version relative to, that is, the driver of version 8.0.22. The official website address is version 8.0.22
and then change the dependency in the POM file to:

<!--MySQL-->
<dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.22</version>
    </dependency>

Another point is that the POM file should include not only driver dependencies, but also mybatis dependencies

<!--mybatis-->
<dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.4.5</version>
    </dependency>