基于python的比赛报名系统设计与实现，使用flask框架以及mysql数据库，主要功能有：注册，登录，个人信息修改，报名，取消报名，评委登录，登录后查看报名选手信息并同意报名，管理员登录后更改公告信息的代码以及数据库以及html设计

这个系统的实现需要以下几个模块：

1. 用户模块：包括注册、登录、修改个人信息等功能。注册时需要填写用户名、密码和邮箱等信息，并进行验证，登录时需要验证用户名和密码是否正确，修改个人信息可以修改用户的基本信息。

2. 报名模块：包括报名和取消报名功能。报名时需要填写比赛名称、参赛选手姓名、联系方式等信息，并进行验证，取消报名可以取消已经报名的比赛。

3. 评委模块：评委登录后可以查看已经报名的选手信息，并进行同意或者拒绝报名的操作。

4. 管理员模块：管理员登录后可以更改公告信息，对数据库进行操作，以及进行html设计等功能。

下面是使用flask框架和mysql数据库实现的基本代码：

1. 用户模块

from flask import Flask, render_template, request, session, redirect, url_for
import pymysql

app = Flask(__name__)
app.secret_key = '123456'

# 连接mysql数据库
db = pymysql.connect(host='localhost', user='root', password='123456', db='competition', charset='utf8')

# 用户注册
@app.route('/register', methods=['GET', 'POST'])
def register():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        email = request.form['email']
        cursor = db.cursor()
        sql = "INSERT INTO users (username, password, email) VALUES (%s, %s, %s)"
        try:
            cursor.execute(sql, (username, password, email))
            db.commit()
            return redirect(url_for('login'))
        except:
            db.rollback()
            return render_template('register.html')
    return render_template('register.html')

# 用户登录
@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        cursor = db.cursor()
        sql = "SELECT * FROM users WHERE username=%s AND password=%s"
        cursor.execute(sql, (username, password))
        user = cursor.fetchone()
        if user:
            session['username'] = user[1]
            return redirect(url_for('index'))
        else:
            return render_template('login.html')
    return render_template('login.html')

# 修改个人信息
@app.route('/profile', methods=['GET', 'POST'])
def profile():
    if 'username' not in session:
        return redirect(url_for('login'))
    if request.method == 'POST':
        username = session['username']
        email = request.form['email']
        cursor = db.cursor()
        sql = "UPDATE users SET email=%s WHERE username=%s"
        cursor.execute(sql, (email, username))
        db.commit()
        return redirect(url_for('index'))
    username = session['username']
    cursor = db.cursor()
    sql = "SELECT * FROM users WHERE username=%s"
    cursor.execute(sql, (username,))
    user = cursor.fetchone()
    return render_template('profile.html', user=user)

# 退出登录
@app.route('/logout')
def logout():
    session.pop('username', None)
    return redirect(url_for('index'))

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

2. 报名模块

# 报名
@app.route('/apply', methods=['GET', 'POST'])
def apply():
    if 'username' not in session:
        return redirect(url_for('login'))
    if request.method == 'POST':
        username = session['username']
        competition = request.form['competition']
        name = request.form['name']
        phone = request.form['phone']
        cursor = db.cursor()
        sql = "INSERT INTO applications (competition, name, phone, username) VALUES (%s, %s, %s, %s)"
        try:
            cursor.execute(sql, (competition, name, phone, username))
            db.commit()
            return redirect(url_for('index'))
        except:
            db.rollback()
            return render_template('apply.html')
    return render_template('apply.html')

# 取消报名
@app.route('/cancel', methods=['GET', 'POST'])
def cancel():
    if 'username' not in session:
        return redirect(url_for('login'))
    if request.method == 'POST':
        id = request.form['id']
        cursor = db.cursor()
        sql = "DELETE FROM applications WHERE id=%s"
        cursor.execute(sql, (id,))
        db.commit()
        return redirect(url_for('index'))
    username = session['username']
    cursor = db.cursor()
    sql = "SELECT * FROM applications WHERE username=%s"
    cursor.execute(sql, (username,))
    applications = cursor.fetchall()
    return render_template('cancel.html', applications=applications)

3. 评委模块

# 评委登录
@app.route('/judge_login', methods=['GET', 'POST'])
def judge_login():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        cursor = db.cursor()
        sql = "SELECT * FROM judges WHERE username=%s AND password=%s"
        cursor.execute(sql, (username, password))
        judge = cursor.fetchone()
        if judge:
            session['judge'] = judge[1]
            return redirect(url_for('judge'))
        else:
            return render_template('judge_login.html')
    return render_template('judge_login.html')

# 查看选手信息
@app.route('/judge', methods=['GET', 'POST'])
def judge():
    if 'judge' not in session:
        return redirect(url_for('judge_login'))
    cursor = db.cursor()
    sql = "SELECT * FROM applications"
    cursor.execute(sql)
    applications = cursor.fetchall()
    return render_template('judge.html', applications=applications)

# 同意报名
@app.route('/agree', methods=['GET', 'POST'])
def agree():
    if 'judge' not in session:
        return redirect(url_for('judge_login'))
    if request.method == 'POST':
        id = request.form['id']
        cursor = db.cursor()
        sql = "UPDATE applications SET status=%s WHERE id=%s"
        cursor.execute(sql, ('已通过', id))
        db.commit()
        return redirect(url_for('judge'))
    return redirect(url_for('judge'))

4. 管理员模块

# 管理员登录
@app.route('/admin_login', methods=['GET', 'POST'])
def admin_login():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        cursor = db.cursor()
        sql = "SELECT * FROM admins WHERE username=%s AND password=%s"
        cursor.execute(sql, (username, password))
        admin = cursor.fetchone()
        if admin:
            session['admin'] = admin[1]
            return redirect(url_for('admin'))
        else:
            return render_template('admin_login.html')
    return render_template('admin_login.html')

# 更改公告信息
@app.route('/admin', methods=['GET', 'POST'])
def admin():
    if 'admin' not in session:
        return redirect(url_for('admin_login'))
    if request.method == 'POST':
        notice = request.form['notice']
        cursor = db.cursor()
        sql = "UPDATE notices SET content=%s WHERE id=1"
        cursor.execute(sql, (notice,))
        db.commit()
    cursor = db.cursor()
    sql = "SELECT * FROM notices WHERE id=1"
    cursor.execute(sql)
    notice = cursor.fetchone()
    return render_template('admin.html', notice=notice[1])

# 对数据库进行操作
@app.route('/sql', methods=['GET', 'POST'])
def sql():
    if 'admin' not in session:
        return redirect(url_for('admin_login'))
    if request.method == 'POST':
        sql = request.form['sql']
        cursor = db.cursor()
        try:
            cursor.execute(sql)
            data = cursor.fetchall()
            db.commit()
            return render_template('sql.html', data=data)
        except:
            db.rollback()
            return render_template('sql.html')
    return render_template('sql.html')

以上是基于python的比赛报名系统设计与实现的基本代码，你可以根据需求进行相应的修改和完善。