框架的學習是需要不斷的融合實踐的，實踐總是要說錯誤的，下面咱們就來看一下新的錯誤類型--時區錯誤。
當然在這之前，我是不知道有這種問題的，指到我的mybatis遇到了下面這個問題：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!
這個是什麼呢？爲什麼會查詢錯誤呢？當你檢查了下面一行的配置文件UserLoginMapper.xml，發現你的驅動，你的密碼，你的賬號都是正確的，但是就是查不了數據庫，這是一種時區錯誤了，現在我們用的是東八區，所以要在mysql中設置一下。步驟如下：
首先找到navicat的導航欄中工具--->命令行界面
然後輸入這一段代碼：
mysql> set global time_zone = '+8:00';
Query OK, 0 rows affected
mysql> commit;
Query OK, 0 rows affected
mysql>
這個時候問題就解決了。
下面附上事故現場：
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)