springboot use problems encountered in the process

A tool Intellij IDEA

Second, the basic problem

1. Database statement

Caused by: java.lang.IllegalStateException: Cannot load driver class: com.mysql.cj.jdbc.Driver 

Solution: Check application.prooerties file database statements: spring.datasource.driver-class-name = com.mysql.cj.jdbc.Driver whether there is a space behind (no spaces)