diff --git "a/42 \346\226\271\345\242\236\345\205\264/\351\241\265\351\235\242.md" "b/42 \346\226\271\345\242\236\345\205\264/\351\241\265\351\235\242.md"
new file mode 100644
index 0000000000000000000000000000000000000000..119f28ce217181368249465d2398ea17ee5ff38a
--- /dev/null
+++ "b/42 \346\226\271\345\242\236\345\205\264/\351\241\265\351\235\242.md"	
@@ -0,0 +1,145 @@
+```java
+package selevert;
+import javax.servlet.ServletException;
+import javax.servlet.annotation.WebServlet;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.sql.*;
+public class All {
+    private static final String user = "root";
+    private static final String pwd = "xflovexz";
+    private static final String url = "jdbc:mysql://localhost:3306/info_all?useSSL=false&useUnicode=true&characterEncoding=utf8";
+
+    static {
+        try {
+            Class.forName("com.mysql.cj.jdbc.Driver");
+        } catch (ClassNotFoundException e) {
+            System.out.println("注册失败");
+            e.printStackTrace();
+        }
+    }
+
+
+    public static Connection getConn() {
+        Connection conn = null;// alt+回车
+        try {
+            conn = DriverManager.getConnection(url, user, pwd);
+        } catch (SQLException e) {
+            System.out.println("获取连接对象失败");
+            e.printStackTrace();
+        }
+        return conn;
+    }
+    public static ResultSet select(String sql, String... keys) {
+        ResultSet res = null;
+        try {
+            Connection coon = getConn();
+            PreparedStatement pre = coon.prepareStatement(sql);
+            for (int i = 0; i < keys.length; i++) {
+                pre.setString((i + 1), keys[i]);
+            }
+            res = pre.executeQuery();
+        } catch (SQLException e) {
+            System.out.println("查询失败");
+            e.printStackTrace();
+        }
+        return res;
+    }
+
+    public static int updata(String sql, String... keys) {
+        int num = 0;
+        try {
+            Connection conn = getConn();
+            // 预编译对象
+            PreparedStatement pre = conn.prepareStatement(sql);
+            for (int i = 0; i < keys.length; i++) {
+                pre.setString((i + 1), keys[i]);
+            }
+            num = pre.executeUpdate();
+        } catch (SQLException e) {
+            System.out.println("更新失败");
+            e.printStackTrace();
+        }
+        return num;
+    }
+
+    public static void delete(String sql, String... keys) {
+        int num = 0;
+        try {
+            Connection conn = getConn();
+            PreparedStatement pre = conn.prepareStatement(sql);
+            for (int i = 0; i < keys.length; i++) {
+                pre.setString((i + 1), keys[i]);
+            }
+            num = pre.executeUpdate();
+            if (num > 0) {
+                System.out.println("删除成功");
+            } else {
+                System.out.println("删除失败");
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public static String[] add(String sql, String... keys) {
+        try {
+            Connection conn = getConn();
+            PreparedStatement pre = conn.prepareStatement(sql);
+            for (int i = 0; i < keys.length; i++) {
+                pre.setString((i + 1), keys[i]);
+            }
+
+            int num = pre.executeUpdate();
+            if (num>0){
+                System.out.println("添加成功");
+            }
+            String sql1 = "select * from info";
+            All.select(sql1);
+        } catch (SQLException e) {
+            System.out.println("禁止输入相同id");
+            e.printStackTrace();
+        }
+        return keys;
+    }
+
+    @WebServlet("/select")
+    public static class K extends HttpServlet {
+        @Override
+        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+            resp.setContentType("text/html;charset=utf-8");
+            // 创建一个响应对象的输出流
+            PrintWriter out = resp.getWriter();
+            String sql = "select * from info";
+            Connection connection = All.getConn();
+            System.out.println(connection);
+            ResultSet res = All.select(sql);
+            out.write("<table border=1 style='margin:auto'> ");
+            out.write("<tr>" +
+                    "<th>编号</th><th>姓名</th><th>性别</th><th>功能</th>" +
+                    "</tr>");
+            try {
+                while (res.next()){
+                    int id = res.getInt("id");
+                    String name = res.getString("name");
+                    String gender = res.getString("gender");
+                    System.out.println(id+name+gender);
+                    out.write("<tr><td>"+id+"</td><td>"+name+"</td><td>"+gender+"</td><td><a href='index.html'><input type='button' value='删除'></a><a href='index.html'><input type='button' value='添加'></a></td></tr>");
+                }
+            } catch (SQLException e) {
+                e.printStackTrace();
+            }
+            out.write("</table>");
+        }
+        @Override
+        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+            super.doPost(req, resp);
+        }
+    }
+}
+
+```
+