feat: 实现教师资料更新、操作日志和系统设置功能

新增教师资料更新功能，包括个人信息修改和密码更新
添加操作日志记录系统，记录用户关键操作
实现系统设置模块，支持动态配置系统参数
重构数据库模型，新增教师表和系统设置表
优化成绩录入逻辑，支持平时分、期中和期末成绩计算
添加数据导出功能，支持学生、教师和成绩数据导出
完善管理员后台，增加统计图表和操作日志查看

backend/models/Score.js

@@ -41,7 +41,7 @@ class Score {
         const sql = `
             INSERT INTO grades (student_id, course_id, teacher_id, final_score, total_score, 
             grade_point, grade_level, created_at, remark) 
-            VALUES (?, ?, ?, ?, ?, ?, ?, NOW(), ?)
+            VALUES (?, ?, ?, ?, ?, ?, ?, datetime('now', 'localtime'), ?)
         `;
         const result = await db.pool.execute(sql, [
             studentId, courseId, teacherId, score, score, gradePoint, gradeLevel, remark
@@ -56,6 +56,78 @@ class Score {
         );
         return rows[0];
     }
+
+    static async findByTeacher(teacherId, filters) {
+        let sql = `
+            SELECT g.*, s.name as student_name, c.course_name
+            FROM grades g
+            JOIN students s ON g.student_id = s.id
+            JOIN courses c ON g.course_id = c.id
+            WHERE c.teacher_id = ?
+        `;
+        const params = [teacherId];
+        
+        if (filters.courseId) {
+            sql += ' AND g.course_id = ?';
+            params.push(filters.courseId);
+        }
+        if (filters.studentName) {
+            sql += ' AND (s.name LIKE ? OR s.id LIKE ?)';
+            params.push(`%${filters.studentName}%`, `%${filters.studentName}%`);
+        }
+        return await db.query(sql, params);
+    }
+
+    static async findCourseStudentsWithGrades(courseId, teacherId) {
+        const sql = `
+            SELECT s.id as student_id, s.name as student_name, 
+                   g.usual_score, g.midterm_score, g.final_score, g.total_score, g.grade_point, g.grade_level,
+                   c.id as course_id, c.course_name
+            FROM students s
+            JOIN classes cl ON s.class = cl.class_name
+            JOIN courses c ON c.class_id = cl.id
+            LEFT JOIN grades g ON s.id = g.student_id AND g.course_id = c.id
+            WHERE c.id = ? AND c.teacher_id = ?
+        `;
+        return await db.query(sql, [courseId, teacherId]);
+    }
+
+    static async upsert(scoreData) {
+        const { 
+            studentId, courseId, teacherId, 
+            usual_score, midterm_score, final_score, score, 
+            gradePoint, gradeLevel, remark 
+        } = scoreData;
+        
+        const existing = await this.findByStudentAndCourse(studentId, courseId);
+        
+        // 处理参数：如果是 undefined 或空字符串，则设为 null
+        const sanitize = (val) => (val === undefined || val === '' || val === null) ? null : val;
+
+        const params = [
+            sanitize(usual_score), 
+            sanitize(midterm_score), 
+            sanitize(final_score), 
+            sanitize(score), 
+            sanitize(gradePoint), 
+            sanitize(gradeLevel), 
+            sanitize(remark)
+        ];
+        
+        if (existing) {
+             const sql = `UPDATE grades SET usual_score=?, midterm_score=?, final_score=?, total_score=?, grade_point=?, grade_level=?, remark=? WHERE id=?`;
+             await db.query(sql, [...params, existing.id]);
+             return existing.id;
+        } else {
+             const sql = `INSERT INTO grades (student_id, course_id, teacher_id, usual_score, midterm_score, final_score, total_score, grade_point, grade_level, created_at, remark) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, datetime('now', 'localtime'), ?)`;
+             const insertParams = [
+                 studentId, courseId, teacherId,
+                 ...params
+             ];
+             const result = await db.query(sql, insertParams);
+             return result.insertId;
+        }
+    }
 }
 
 module.exports = Score;