refactor(database): 迁移到SQLite并清理旧MySQL相关代码

移除MySQL相关依赖和配置，完全迁移到SQLite数据库
删除不再需要的MySQL迁移脚本和备份文件
更新README文档说明新的数据库架构
在init_db.js中整合教师和系统设置表的初始化逻辑

backend/init_db.js

@@ -28,6 +28,13 @@ const insertStudent = async (student) => {
     );
 };
 
+const insertTeacher = async (teacher) => {
+    await run(
+        'INSERT INTO teachers (id, name, department, title, contact_info) VALUES (?, ?, ?, ?, ?)',
+        [teacher.id, teacher.name, teacher.department, teacher.title, teacher.contact_info]
+    );
+};
+
 const insertClass = async (cls) => {
     return await run(
         'INSERT INTO classes (class_name, grade, major, teacher_id) VALUES (?, ?, ?, ?)',
@@ -91,6 +98,8 @@ const init = async () => {
         await run('DROP TABLE IF EXISTS students');
         await run('DROP TABLE IF EXISTS users');
         await run('DROP TABLE IF EXISTS operation_logs');
+        await run('DROP TABLE IF EXISTS system_settings');
+        await run('DROP TABLE IF EXISTS teachers');
 
         // Create tables
         console.log('创建表结构...');
@@ -174,8 +183,38 @@ const init = async () => {
             )
         `);
 
+        await run(`
+            CREATE TABLE teachers (
+                id TEXT PRIMARY KEY,
+                name TEXT NOT NULL,
+                department TEXT,
+                title TEXT,
+                contact_info TEXT,
+                FOREIGN KEY (id) REFERENCES users(id) ON DELETE CASCADE
+            )
+        `);
+
+        await run(`
+            CREATE TABLE system_settings (
+                key TEXT PRIMARY KEY,
+                value TEXT
+            )
+        `);
+
         console.log('生成基础数据...');
 
+        // 0. System Settings
+        const defaultSettings = [
+            ['system_name', '学校成绩管理系统'],
+            ['current_semester', '2023-2024-2'],
+            ['allow_course_selection', '1'],
+            ['allow_grade_check', '1']
+        ];
+        
+        for (const [key, value] of defaultSettings) {
+            await run('INSERT OR IGNORE INTO system_settings (key, value) VALUES (?, ?)', [key, value]);
+        }
+
         // 1. Admin
         await insertUser({
             id: 'admin',
@@ -187,9 +226,16 @@ const init = async () => {
 
         // 2. Teachers (20 teachers)
         const teachers = [];
+        const departments = ['计算机学院', '软件学院', '信息工程学院', '理学院', '外国语学院'];
+        const titles = ['教授', '副教授', '讲师', '助教'];
+
         for (let i = 1; i <= 20; i++) {
             const id = `T${1000 + i}`;
             const name = `教师${String.fromCharCode(65 + (i % 26))}${i}`;
+            const dept = departments[i % departments.length];
+            const title = titles[i % titles.length];
+            const contact = `139${Math.floor(Math.random() * 90000000 + 10000000)}`;
+
             await insertUser({
                 id,
                 name,
@@ -197,6 +243,15 @@ const init = async () => {
                 role: 'teacher',
                 class: null
             });
+
+            await insertTeacher({
+                id,
+                name,
+                department: dept,
+                title: title,
+                contact_info: contact
+            });
+
             teachers.push(id);
         }
 

backend/package.json

@@ -13,9 +13,7 @@
     "cors": "^2.8.5",
     "dotenv": "^16.3.1",
     "express": "^4.18.2",
-    "express-mysql-session": "^3.0.0",
     "express-session": "^1.17.3",
-    "mysql2": "^3.6.0",
     "sqlite3": "^5.1.7"
   },
   "devDependencies": {

backend/scripts/fix_teachers.js

@@ -1,31 +0,0 @@
-const db = require('../config/database');
-
-async function fixTeachers() {
-    const departments = ['计算机学院', '软件学院', '信息工程学院', '理学院', '外国语学院'];
-    const titles = ['教授', '副教授', '讲师', '助教'];
-    
-    try {
-        const teachers = await db.query('SELECT id FROM teachers');
-        for (let i = 0; i < teachers.length; i++) {
-            const dept = departments[i % departments.length];
-            const title = titles[i % titles.length];
-            const contact = `139${Math.floor(Math.random() * 90000000 + 10000000)}`;
-            
-            await db.query(
-                'UPDATE teachers SET department = ?, title = ?, contact_info = ? WHERE id = ?',
-                [dept, title, contact, teachers[i].id]
-            );
-            
-            // Also sync back to users table's class field if needed (though we'll use teachers table now)
-            await db.query(
-                'UPDATE users SET class = ? WHERE id = ?',
-                [dept, teachers[i].id]
-            );
-        }
-        console.log('教师信息修复完成！');
-    } catch (err) {
-        console.error('修复失败:', err);
-    }
-}
-
-fixTeachers();

backend/scripts/migrate_v2.js

@@ -1,48 +0,0 @@
-const db = require('../config/database');
-
-async function migrate() {
-    try {
-        console.log('Starting migration v2...');
-        
-        // 1. System Settings Table
-        await db.query(`
-            CREATE TABLE IF NOT EXISTS system_settings (
-                key TEXT PRIMARY KEY,
-                value TEXT
-            )
-        `);
-        
-        // Default settings
-        const defaultSettings = [
-            ['system_name', '学校成绩管理系统'],
-            ['current_semester', '2023-2024-2'],
-            ['allow_course_selection', '1'],
-            ['allow_grade_check', '1']
-        ];
-        
-        for (const [key, value] of defaultSettings) {
-            await db.query('INSERT OR IGNORE INTO system_settings (key, value) VALUES (?, ?)', [key, value]);
-        }
-        
-        // 2. Operation Logs Table
-        await db.query(`
-            CREATE TABLE IF NOT EXISTS operation_logs (
-                id INTEGER PRIMARY KEY AUTOINCREMENT,
-                user_id TEXT,
-                operation_type TEXT,
-                operation_target TEXT,
-                description TEXT,
-                ip_address TEXT,
-                created_at TEXT DEFAULT (datetime('now', 'localtime'))
-            )
-        `);
-        
-        console.log('Migration v2 completed successfully.');
-        process.exit(0);
-    } catch (error) {
-        console.error('Migration v2 failed:', error);
-        process.exit(1);
-    }
-}
-
-migrate();

backend/scripts/migrate_v3.js

@@ -1,33 +0,0 @@
-const db = require('../config/database');
-
-async function migrate() {
-    console.log('开始执行 v3 迁移: 创建 teachers 表...');
-    
-    try {
-        await db.query(`
-            CREATE TABLE IF NOT EXISTS teachers (
-                id TEXT PRIMARY KEY,
-                name TEXT NOT NULL,
-                department TEXT,
-                title TEXT,
-                contact_info TEXT,
-                FOREIGN KEY (id) REFERENCES users(id) ON DELETE CASCADE
-            )
-        `);
-
-        // 从 users 表中迁移现有的教师数据
-        const teachers = await db.query('SELECT id, name, class FROM users WHERE role = "teacher"');
-        for (const t of teachers) {
-            await db.query(
-                'INSERT OR IGNORE INTO teachers (id, name, department) VALUES (?, ?, ?)',
-                [t.id, t.name, t.class]
-            );
-        }
-
-        console.log('v3 迁移成功！');
-    } catch (err) {
-        console.error('v3 迁移失败:', err);
-    }
-}
-
-migrate();

backend/server.js

@@ -1,7 +1,6 @@
 const express = require('express');
 const cors = require('cors');
 const session = require('express-session');
-// const MySQLStore = require('express-mysql-session')(session);
 const path = require('path');
 require('dotenv').config();
 
@@ -27,26 +26,9 @@ app.use(cors({
 app.use(express.json());
 app.use(express.urlencoded({ extended: true }));
 
-// Session
-/*
-const sessionStore = new MySQLStore({
-    expiration: 86400000,
-    createDatabaseTable: true,
-    schema: {
-        tableName: 'sessions',
-        columnNames: {
-            session_id: 'session_id',
-            expires: 'expires',
-            data: 'data'
-        }
-    }
-}, db.pool);
-*/
-
 app.use(session({
     key: 'session_cookie',
     secret: process.env.SESSION_SECRET || 'your-secret-key',
-    // store: sessionStore, // Use MemoryStore for SQLite migration simplification
     resave: false,
     saveUninitialized: false,
     cookie: {