搭建一个考试系统，使其具有自动判卷，查询，统计等功能，代码书写

这是一个比较复杂的项目，需要设计合理的数据库结构和后端逻辑，以下是一个简单的代码示例：

1. 数据库设计

考试系统需要存储考生信息、试题信息、考试记录等数据，因此需要设计相应的表结构。这里给出一个简化的表结构示例：

CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(50) NOT NULL,
  `password` varchar(50) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `exam` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(100) NOT NULL,
  `start_time` datetime NOT NULL,
  `end_time` datetime NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `question` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `exam_id` int(11) NOT NULL,
  `content` text NOT NULL,
  `answer` text NOT NULL,
  PRIMARY KEY (`id`),
  KEY `exam_id` (`exam_id`),
  CONSTRAINT `question_ibfk_1` FOREIGN KEY (`exam_id`) REFERENCES `exam` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `record` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` int(11) NOT NULL,
  `exam_id` int(11) NOT NULL,
  `score` int(11) NOT NULL,
  `submit_time` datetime NOT NULL,
  PRIMARY KEY (`id`),
  KEY `user_id` (`user_id`),
  KEY `exam_id` (`exam_id`),
  CONSTRAINT `record_ibfk_1` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `record_ibfk_2` FOREIGN KEY (`exam_id`) REFERENCES `exam` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

2. 后端代码

接下来是后端代码的示例，使用了Python的Flask框架：

from flask import Flask, jsonify, request
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://username:password@hostname/database'
db = SQLAlchemy(app)

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(50), nullable=False)
    password = db.Column(db.String(50), nullable=False)

class Exam(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(100), nullable=False)
    start_time = db.Column(db.DateTime, nullable=False)
    end_time = db.Column(db.DateTime, nullable=False)

class Question(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    exam_id = db.Column(db.Integer, db.ForeignKey('exam.id', ondelete='CASCADE'), nullable=False)
    content = db.Column(db.Text, nullable=False)
    answer = db.Column(db.Text, nullable=False)

class Record(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    user_id = db.Column(db.Integer, db.ForeignKey('user.id', ondelete='CASCADE'), nullable=False)
    exam_id = db.Column(db.Integer, db.ForeignKey('exam.id', ondelete='CASCADE'), nullable=False)
    score = db.Column(db.Integer, nullable=False)
    submit_time = db.Column(db.DateTime, nullable=False)

@app.route('/login', methods=['POST'])
def login():
    data = request.get_json()
    user = User.query.filter_by(name=data['name'], password=data['password']).first()
    if user:
        return jsonify({'result': 'success'})
    else:
        return jsonify({'result': 'failure'})

@app.route('/exam', methods=['GET'])
def get_exams():
    exams = Exam.query.all()
    result = [{'id': exam.id, 'title': exam.title, 'start_time': exam.start_time, 'end_time': exam.end_time} for exam in exams]
    return jsonify(result)

@app.route('/exam/<int:exam_id>/question', methods=['GET'])
def get_questions(exam_id):
    questions = Question.query.filter_by(exam_id=exam_id).all()
    result = [{'id': question.id, 'content': question.content} for question in questions]
    return jsonify(result)

@app.route('/exam/<int:exam_id>/submit', methods=['POST'])
def submit_exam(exam_id):
    data = request.get_json()
    user_id = data['user_id']
    answers = data['answers']
    questions = Question.query.filter_by(exam_id=exam_id).all()
    score = 0
    for i, question in enumerate(questions):
        if question.answer == answers[i]:
            score += 1
    record = Record(user_id=user_id, exam_id=exam_id, score=score, submit_time=datetime.now())
    db.session.add(record)
    db.session.commit()
    return jsonify({'result': 'success', 'score': score})

if __name__ == '__main__':
    app.run()

3. 前端界面

最后是前端界面的示例，使用了Bootstrap框架：

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>考试系统</title>
    <link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css">
    <script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>
    <script src="https://cdn.bootcss.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
</head>
<body>
    <div class="container">
        <h1>考试系统</h1>
        <form id="login-form">
            <div class="form-group">
                <label for="name">用户名</label>
                <input type="text" class="form-control" id="name" name="name">
            </div>
            <div class="form-group">
                <label for="password">密码</label>
                <input type="password" class="form-control" id="password" name="password">
            </div>
            <button type="submit" class="btn btn-primary">登录</button>
        </form>
        <hr>
        <div id="exam-list">
            <h2>考试列表</h2>
            <table class="table table-striped">
                <thead>
                    <tr>
                        <th>#</th>
                        <th>标题</th>
                        <th>开始时间</th>
                        <th>结束时间</th>
                        <th>操作</th>
                    </tr>
                </thead>
                <tbody>
                </tbody>
            </table>
        </div>
        <div id="question-list">
            <h2>试题列表</h2>
            <div class="panel-group" id="accordion">
            </div>
            <button type="button" class="btn btn-primary" id="submit-btn" style="display: none;">提交</button>
        </div>
    </div>
    <script>
        $(function() {
            $('#login-form').submit(function(event) {
                event.preventDefault();
                var name = $('#name').val();
                var password = $('#password').val();
                $.ajax({
                    url: '/login',
                    type: 'POST',
                    dataType: 'json',
                    data: JSON.stringify({name: name, password: password}),
                    contentType: 'application/json',
                    success: function(data) {
                        if (data.result == 'success') {
                            loadExams();
                        } else {
                            alert('登录失败');
                        }
                    },
                    error: function() {
                        alert('网络错误');
                    }
                });
            });

            function loadExams() {
                $.get('/exam', function(data) {
                    var tbody = $('#exam-list table tbody');
                    tbody.empty();
                    for (var i = 0; i < data.length; i++) {
                        var exam = data[i];
                        var tr = $('<tr></tr>');
                        tr.append($('<td></td>').text(exam.id));
                        tr.append($('<td></td>').text(exam.title));
                        tr.append($('<td></td>').text(exam.start_time));
                        tr.append($('<td></td>').text(exam.end_time));
                        var td = $('<td></td>');
                        var button = $('<button></button>').text('开始考试').addClass('btn btn-primary');
                        button.click(function(exam_id) {
                            return function() {
                                loadQuestions(exam_id);
                            }
                        }(exam.id));
                        td.append(button);
                        tr.append(td);
                        tbody.append(tr);
                    }
                });
            }

            function loadQuestions(exam_id) {
                $.get('/exam/' + exam_id + '/question', function(data) {
                    var accordion = $('#accordion');
                    accordion.empty();
                    for (var i = 0; i < data.length; i++) {
                        var question = data[i];
                        var panel = $('<div></div>').addClass('panel panel-default');
                        var heading = $('<div></div>').addClass('panel-heading');
                        var title = $('<h4></h4>').addClass('panel-title');
                        var link = $('<a></a>').attr('data-toggle', 'collapse').attr('data-parent', '#accordion')
                            .attr('href', '#collapse' + i).text(question.content);
                        title.append(link);
                        heading.append(title);
                        panel.append(heading);
                        var body = $('<div></div>').addClass('panel-collapse collapse').attr('id', 'collapse' + i);
                        var inner = $('<div></div>').addClass('panel-body');
                        inner.append($('<textarea></textarea>').addClass('form-control').attr('rows', '5').attr('name', 'answer-' + i));
                        body.append(inner);
                        panel.append(body);
                        accordion.append(panel);
                    }
                    $('#submit-btn').show();
                    $('#submit-btn').unbind('click').click(function() {
                        submitExam(exam_id);
                    });
                });
            }

            function submitExam(exam_id) {
                var answers = [];
                $('#question-list textarea').each(function() {
                    answers.push($(this).val());
                });
                $.ajax({
                    url: '/exam/' + exam_id + '/submit',
                    type: 'POST',
                    dataType: 'json',
                    data: JSON.stringify({user_id: 1, answers: answers}),
                    contentType: 'application/json',
                    success: function(data) {
                        alert('得分：' + data.score);
                    },
                    error: function() {
                        alert('网络错误');
                    }
                });
            }

            loadExams();
        });
    </script>
</body>
</html>

以上代码仅供参考，实际项目还需要进一步完善和优化。