①创建index.jsp用户管理系统查询所有用户信息列表查②创建FindAllServlet@WebServlet(urlPatterns = “/findAllServlet”)public class FindAllServlet extends HttpServlet{protected void doGet(HttpServletRequest req, HttpServletRespon

加判空就好，null无法插入到字段当中。

添加缺失的配置信息即可解决此问题。解决办法，找到配置文件。

出现下述报错且一直刷：Discovered coordinator tbds-172-16-122-43:6667 (id: 2147482646 rack: null) 2原因是hosts映射没配置好：C:\Windows\System32\drivers\etc改成这样既可注意换行！！！

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(S