数据库连接出问题了。

2022-04-26 11:51:17 711 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

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不懂就问，数据库和visual studio连接出问题怎么办 using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Data; using System.Data.SqlClient; using System.Windows.Forms; namespace HoteManage { class DBHelper { private static string co 阅读详情

百度找不到是什么原因，求各位大佬帮帮忙，谢谢！

严重: 在路径为/News的上下文中，Servlet[DispatcherServlet]的Servlet.service（）引发了具有根本原因的异常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 com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
### The error may exist in file [D:\Eclipse\WorkSpace\.metadata\.plugins\org.eclipse.wst.server.core\tmp1\wtpwebapps\News\WEB-INF\classes\config\mybatis\mapper\admin\NewsCategoryMapper.xml]
### The error may involve com.ischoolbar.programmer.dao.admin.NewsCategoryDao.findAll
### The error occurred while executing a query
### Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
java.lang.NullPointerException: Cannot invoke "java.util.Map.get(Object)" because "this.serverVariables" is null

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