给出代码实现已有用户表，菜单表，角色表的管理操作，如何实现对用户角色表和菜单角色表的管理擦做

由于这个问题需要涉及到数据库操作，因此我提供一个简单的示例代码，假设使用MySQL数据库，使用Python语言，使用Flask框架，仅供参考：

1. 定义数据表结构

from flask_sqlalchemy import SQLAlchemy

db = SQLAlchemy()

# 用户表
class User(db.Model):
    __tablename__ = 'users'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64), unique=True)
    password = db.Column(db.String(128))
    roles = db.relationship('UserRole', backref='user', lazy='dynamic')

# 菜单表
class Menu(db.Model):
    __tablename__ = 'menus'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64), unique=True)
    roles = db.relationship('MenuRole', backref='menu', lazy='dynamic')

# 角色表
class Role(db.Model):
    __tablename__ = 'roles'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64), unique=True)

# 用户角色表
class UserRole(db.Model):
    __tablename__ = 'user_roles'
    id = db.Column(db.Integer, primary_key=True)
    user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
    role_id = db.Column(db.Integer, db.ForeignKey('roles.id'))

# 菜单角色表
class MenuRole(db.Model):
    __tablename__ = 'menu_roles'
    id = db.Column(db.Integer, primary_key=True)
    menu_id = db.Column(db.Integer, db.ForeignKey('menus.id'))
    role_id = db.Column(db.Integer, db.ForeignKey('roles.id'))

2. 创建管理界面

from flask import Flask, render_template, request, redirect, url_for
from flask_wtf import FlaskForm
from wtforms import StringField, PasswordField, SubmitField, SelectMultipleField
from wtforms.validators import DataRequired
from flask_bootstrap import Bootstrap

app = Flask(__name__)
app.config['SECRET_KEY'] = 'your secret key'
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://username:password@localhost/database'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False

bootstrap = Bootstrap(app)
db.init_app(app)

# 定义表单
class UserForm(FlaskForm):
    name = StringField('用户名', validators=[DataRequired()])
    password = PasswordField('密码', validators=[DataRequired()])
    roles = SelectMultipleField('角色', coerce=int)
    submit = SubmitField('提交')

class MenuForm(FlaskForm):
    name = StringField('菜单名', validators=[DataRequired()])
    roles = SelectMultipleField('角色', coerce=int)
    submit = SubmitField('提交')

class RoleForm(FlaskForm):
    name = StringField('角色名', validators=[DataRequired()])
    submit = SubmitField('提交')

# 定义路由
@app.route('/users', methods=['GET', 'POST'])
def users():
    form = UserForm()
    if form.validate_on_submit():
        name = form.name.data
        password = form.password.data
        roles = Role.query.filter(Role.id.in_(form.roles.data)).all()
        user = User(name=name, password=password, roles=roles)
        db.session.add(user)
        db.session.commit()
        return redirect(url_for('users'))
    users = User.query.all()
    return render_template('users.html', users=users, form=form)

@app.route('/menus', methods=['GET', 'POST'])
def menus():
    form = MenuForm()
    if form.validate_on_submit():
        name = form.name.data
        roles = Role.query.filter(Role.id.in_(form.roles.data)).all()
        menu = Menu(name=name, roles=roles)
        db.session.add(menu)
        db.session.commit()
        return redirect(url_for('menus'))
    menus = Menu.query.all()
    return render_template('menus.html', menus=menus, form=form)

@app.route('/roles', methods=['GET', 'POST'])
def roles():
    form = RoleForm()
    if form.validate_on_submit():
        name = form.name.data
        role = Role(name=name)
        db.session.add(role)
        db.session.commit()
        return redirect(url_for('roles'))
    roles = Role.query.all()
    return render_template('roles.html', roles=roles, form=form)

3. 实现关联操作

# 在用户表中查询用户及其关联的角色
@app.route('/user/<int:user_id>/roles', methods=['GET', 'POST'])
def user_roles(user_id):
    user = User.query.get_or_404(user_id)
    if request.method == 'POST':
        roles = Role.query.filter(Role.id.in_(request.form.getlist('roles'))).all()
        user.roles = roles
        db.session.commit()
        return redirect(url_for('users'))
    form = UserForm(obj=user)
    form.roles.choices = [(r.id, r.name) for r in Role.query.all()]
    form.roles.data = [r.id for r in user.roles]
    return render_template('user_roles.html', user=user, form=form)

# 在菜单表中查询菜单及其关联的角色
@app.route('/menu/<int:menu_id>/roles', methods=['GET', 'POST'])
def menu_roles(menu_id):
    menu = Menu.query.get_or_404(menu_id)
    if request.method == 'POST':
        roles = Role.query.filter(Role.id.in_(request.form.getlist('roles'))).all()
        menu.roles = roles
        db.session.commit()
        return redirect(url_for('menus'))
    form = MenuForm(obj=menu)
    form.roles.choices = [(r.id, r.name) for r in Role.query.all()]
    form.roles.data = [r.id for r in menu.roles]
    return render_template('menu_roles.html', menu=menu, form=form)

这个示例代码仅供参考，实际开发中还需要考虑更多的细节和安全性问题。