框架的学习是需要不断的融合实践的，实践总是要说错误的，下面咱们就来看一下新的错误类型--时区错误。
当然在这之前，我是不知道有这种问题的，指到我的mybatis遇到了下面这个问题：Error querying database
### Error querying database. Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not getJDBC Connection; nested exception is java.sql.SQLException: Connections could not be acquired from the underlying database!
### The error may exist in com/wj/mapper/UserLoginMapper.xml
### The error may involve com.wj.mapper.UserLoginMapper.selectByName
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is java.sql.SQLException: Connections could not be acquired from the underlying database!
这个是什么呢？为什么会查询错误呢？当你检查了下面一行的配置文件UserLoginMapper.xml，发现你的驱动，你的密码，你的账号都是正确的，但是就是查不了数据库，这是一种时区错误了，现在我们用的是东八区，所以要在mysql中设置一下。步骤如下：
首先找到navicat的导航栏中工具--->命令行界面
然后输入这一段代码：
mysql> set global time_zone = '+8:00';
Query OK, 0 rows affected
mysql> commit;
Query OK, 0 rows affected
mysql>
这个时候问题就解决了。
下面附上事故现场：
org.springframework.web.util.NestedServletException: 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: Could not get JDBC Connection; nested exception is java.sql.SQLException: Connections could not be acquired from the underlying database!
### The error may exist in com/wj/mapper/UserLoginMapper.xml
### The error may involve com.wj.mapper.UserLoginMapper.selectByName
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is java.sql.SQLException: Connections could not be acquired from the underlying database!
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)
org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
javax.servlet.http.HttpServlet.service(HttpServlet.java:731)