通过用户模型，对数据库进行增删改查操作。

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
import config

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


# db.create_all()

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)

#修改
user = User.query.filter(User.username == 'zp').first()
user.password='1111'
print(user.username,user.password)
db.session.commit()
#删除
user = User.query.filter(User.username == 'zp').first()
print(user.username,user.password)
db.session.delete(user)
db.session.commit()
#添加
user=User(username='zp',password='1111')
db.session.add(user)
db.session.commit()

'''
db.create_all()
user=User.query.filter(User.username=='chen1115').first()
user.password='11111'
db.session.commit()

'''
@app.route('/')
def hello_world():
    return 'Hello World!'


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