diff --git a/Server/3/.gitignore b/Server/3/.gitignore
new file mode 100644
index 0000000..f52e6f5
--- /dev/null
+++ b/Server/3/.gitignore
@@ -0,0 +1,2 @@
+node_modules
+pnpm-lock.yaml
\ No newline at end of file
diff --git a/Server/3/app.js b/Server/3/app.js
new file mode 100644
index 0000000..4c6a0ea
--- /dev/null
+++ b/Server/3/app.js
@@ -0,0 +1,94 @@
+const express = require("express");
+const session = require("express-session");
+const bodyParser = require("body-parser");
+const mysql = require("mysql2");
+const cors = require("cors")
+
+const app = express();
+const port = 3000;
+
+const db = mysql.createConnection({
+    host: "127.0.0.1",
+    port: 3306,
+    user: "root",
+    password: "123456",
+    database: "express_db"
+})
+
+db.connect((err) => {
+    if (err) {
+        console.log("Error connect to MySQL database:", err);
+        return;
+    }
+    console.log("Connected to MySQL database");
+})
+
+
+app.use(bodyParser.urlencoded({ extended: false }));
+app.use(bodyParser.json());
+app.use(cors({
+    origin: "http://127.0.0.1:3000",
+    method: ["GET", "POST"],
+    allowedHeaders: ['Content-Type', "Authorization"]
+}))
+app.use(session({
+    secret: "secret-key",
+    resave: false,
+    saveUninitialized: true,
+    cookie: { secret: false }
+}));
+
+const isAuthorization = (req, res, next) => {
+    if (req.session.user)
+        next();
+    else
+        res.status(401).send("You are not authorization")
+};
+
+app.post("/login", (req, res) => {
+    const { username, password } = req.body;
+    const sql = "SELECT username, password FROM users WHERE username = ? AND password = ?"
+    db.query(sql, [username, password], (err, result) => {
+        if (err) {
+            res.status(500).send("query database failed");
+            return;
+        }
+
+        if (result.length > 0) {
+            req.session.user = result[0];
+            res.send("Login successful!");
+        } else {
+            res.send("Login failed.");
+        }
+    })
+});
+
+app.post("/register", (req, res) => {
+    const { username, password } = req.body;
+    const sql = "INSERT INTO users (username, password) VALUES (?, ?)"
+    db.query(sql, [username, password], (err, result) => {
+        if (err) {
+            console.log(err);
+
+            res.status(500).send("query database failed");
+            return
+        }
+
+        res.send("Register successful!");
+    })
+})
+
+app.get("/ucenter", isAuthorization, (req, res) => {
+    const user = req.session.user;
+    res.send(`hello ${user.username}, welcome to ucenter`);
+})
+
+app.get("/orders", isAuthorization, (req, res) => {
+    const user = req.session.user;
+    res.send(`hello ${user.username}, welcome to orders`);
+})
+
+app.listen(port, () => {
+    console.log(`Server is running on http://localhost:${port}`);
+
+})
diff --git a/Server/3/package.json b/Server/3/package.json
new file mode 100644
index 0000000..36b37c0
--- /dev/null
+++ b/Server/3/package.json
@@ -0,0 +1,20 @@
+{
+  "name": "3",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "packageManager": "pnpm@10.14.0",
+  "dependencies": {
+    "body-parser": "^2.2.1",
+    "cors": "^2.8.5",
+    "express": "^5.2.1",
+    "express-session": "^1.18.2",
+    "mysql2": "^3.16.0"
+  }
+}
diff --git a/Server/README.md b/Server/README.md
index fc79bec..1ba1c2e 100644
--- a/Server/README.md
+++ b/Server/README.md
@@ -13,6 +13,7 @@
 .
 ├── 1  # 课堂练习1
 ├── 2  # 课堂练习2
+├── 3  # 课堂练习3
 └── tests  # 实验文件夹
     ├── test1  # 实验1
     ├── test2  # 实验2
@@ -21,5 +22,7 @@
     ├── test5  # 实验5
     ├── test6  # 实验6
     ├── test7  # 实验7
+    │   ├── 7.1  # 实验7.1
+    │   └── 7.2  # 实验7.2
     └── test8  # 实验8
 ```