springboot遇到java.sql.SQLSyntaxErrorException: Unknown database问题

java.sql.SQLSyntaxErrorException: Unknown database ‘springboot’

ERROR o.a.c.c.C.[Tomcat].[localhost].[/].[dispatcherServlet] - Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLSyntaxErrorException: Unknown database 'springboot'
### The error may exist in com/wumeng/canal_statistics/modules/report/mapper/OrderMapper.java (best guess)
### The error may involve com.wumeng.canal_statistics.modules.report.mapper.OrderMapper.selectList
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLSyntaxErrorException: Unknown database 'springboot'] with root cause
java.sql.SQLSyntaxErrorException: Unknown database 'springboot'

解决方法：

检查数据库的配置的数据库是否存在springboot的database。

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/springboot?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=GMT%2B8
spring.datasource.username=root
spring.datasource.password=123456

如果不存在，就新建一个或者使用存在的数据库表。