diff --git "a/12 \350\213\217\344\273\244\351\271\217/20230524_12 \350\213\217\344\273\244\351\271\217 \345\242\236\345\210\240\346\224\271.md" "b/12 \350\213\217\344\273\244\351\271\217/20230524_12 \350\213\217\344\273\244\351\271\217 \345\242\236\345\210\240\346\224\271.md"
new file mode 100644
index 0000000000000000000000000000000000000000..597a1662b4796fb7a8c5246299e9e14bad8c2298
--- /dev/null
+++ "b/12 \350\213\217\344\273\244\351\271\217/20230524_12 \350\213\217\344\273\244\351\271\217 \345\242\236\345\210\240\346\224\271.md"	
@@ -0,0 +1,121 @@
+## 添加
+
+```java
+import javax.servlet.*;
+import javax.servlet.http.*;
+import javax.servlet.annotation.*;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.sql.SQLException;
+
+@WebServlet("/addStu")
+public class addStudent extends HttpServlet {
+    @Override
+    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        request.setCharacterEncoding("utf-8");
+        response.setContentType("text/html;charset=utf-8");
+    }
+
+    @Override
+    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        request.setCharacterEncoding("utf-8");
+        response.setContentType("text/html;charset=utf-8");
+        PrintWriter writer = response.getWriter();
+        String sql = "insert into stu values (?,?,?)";
+        String id = request.getParameter("id");
+        String name = request.getParameter("name");
+        String sex = request.getParameter("sex");
+        try {
+            int i = DBUtil.Update(sql, id, name, sex);
+            if (i>0){
+                writer.write("添加成功");
+            }else {
+                writer.write("添加失败");
+            }
+        } catch (SQLException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}
+```
+
+## 删除
+
+```java
+import javax.servlet.*;
+import javax.servlet.http.*;
+import javax.servlet.annotation.*;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.sql.SQLException;
+
+@WebServlet("/deleteStu")
+public class deleteStudent extends HttpServlet {
+    @Override
+    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+
+    }
+
+    @Override
+    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        request.setCharacterEncoding("utf-8");
+        response.setContentType("text/html;charset=utf-8");
+        PrintWriter writer = response.getWriter();
+        String sql = "delete from stu where id = ?";
+        String id = request.getParameter("id");
+        try {
+            int i = DBUtil.Update(sql, id);
+            if (i>0){
+                writer.write("删除成功");
+            }else {
+                writer.write("删除失败");
+            }
+        } catch (SQLException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}
+
+```
+
+## 修改
+
+```java
+import javax.servlet.*;
+import javax.servlet.http.*;
+import javax.servlet.annotation.*;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.sql.SQLException;
+
+@WebServlet("/updateStu")
+public class updateStudent extends HttpServlet {
+    @Override
+    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+
+    }
+
+    @Override
+    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
+        request.setCharacterEncoding("utf-8");
+        response.setContentType("text/html;charset=utf8");
+        PrintWriter writer = response.getWriter();
+        String sql = "update stu set name=?,sex=? where id=?";
+        String id = request.getParameter("id");
+        String name = request.getParameter("name");
+        String sex = request.getParameter("sex");
+        try {
+            int i = DBUtil.Update(sql, name, sex, id);
+            if (i>0){
+                writer.write("修改成功");
+            }else {
+                writer.write("修改失败");
+            }
+        } catch (SQLException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}
+
+```
+