通过用户模型，对数据库进行增删改查操作。

from flask import Flask,render_template
from flask_sqlalchemy import SQLAlchemy
import config

app = Flask(__name__)
app.config.from_object(config)
db=SQLAlchemy(app)


class User(db.Model):
    __tablename__=‘user‘
    id = db.Column(db.Integer,primary_key=True,autoincrement=True)
    username=db.Column(db.String(20),nullable=False)
    password=db.Column(db.String(20),nullable=False)

db.create_all()
#删除
user = User.query.filter(User.username == ‘123‘).first()
db.session.delete(user)
db.session.commit()

#修改
user.password = ‘456‘
print(user.username,user.password)
db.session.commit()

#增加
user = User(username = ‘789‘,password = ‘123456‘)
db.session.add(user)
db.session.commit()





@app.route(‘/‘)
def index():
    return render_template("daohang.html")

@app.route(‘/denglu‘)
def login():
    return render_template("denglu.html")

@app.route(‘/zhuce‘)
def register():
    return render_template("zhuce.html")

@app.route(‘/fabu‘)
def fankui():
    return render_template("fabu.html")

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