<%@page import="java.sql.DriverManager"%> <%@page import="java.sql.PreparedStatement"%> <%@page import="java.sql.ResultSet"%> <%@page import="java.sql.Connection"%> <%@page import="java.sql.Statement"%> <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> My JSP 'AddHandle.jsp' starting page <% request.setCharacterEncoding("UTF-8"); String id = request.getParameter("id"); String name = request.getParameter("name"); String _class = request.getParameter("_class"); String sex = request.getParameter("sex"); String project = request.getParameter("project"); String grade = request.getParameter("grade"); String ranking = request.getParameter("ranking"); String sqlQuery = "INSERT INTO `ydh`.`grade` (`num`, `name`, `class`, `sex`, `project`, `grade`, `ranking`) VALUES (?, ?, ?, ?, ?,?,?)"; String sqlid = "SELECT * FROM ydh.grade where num='"+id+"'"; Connection con = null; Statement stat = null; ResultSet rs = null; PreparedStatement ps = null; try{ Class.forName("com.mysql.cj.jdbc.Driver"); con = DriverManager.getConnection("jdbc:mysql://localhost:3306/ydh?serverTimezone=UTC&useSSL=false&useUnicode=true&characterEncoding=utf8","root","123456"); stat = con.createStatement(); rs = stat.executeQuery(sqlid); if(rs.next()){ out.print(""); }else{ ps = con.prepareStatement(sqlQuery); ps.setString(1,id); ps.setString(2,name); ps.setString(3,_class); ps.setString(4,sex); ps.setString(5,project); ps.setString(6,grade); ps.setString(7,ranking); ps.executeUpdate(); out.print(""); ps.close(); } rs.close(); stat.close(); con.close(); }catch (Exception e){ e.printStackTrace(); } %>