ERROR 5336 --- [nio-8070-exec-1] o.a.c.c.C.[.[.[/].[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.SQLException: com.mysql.cj.jdbc.Driver

### The error may exist in file [C:\Users\dell\IdeaProjects\miaosha1\target\classes\mapping\UserDOMapper.xml]

### The error may involve com.miaoshaproject.dao.UserDOMapper.selectByPrimaryKey

### The error occurred while executing a query

### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection; nested exception is java.sql.SQLException: com.mysql.cj.jdbc.Driver] with root cause