通过用户模型，对数据库进行增删改查操作。

增加：
user = 
db.session.add(user)
db.session.commit()

查询：
User.query.filter(User.username == 'mis1114').first()

修改：
user.password = '111111'
db.session.commit()

删除：
db.session.delete(user)
db.session.commit()

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

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)
    nickname = db.Column(db.String(20))

#db.create_all()

user=User(username='mis0106',password='123456')
db.session.add(user)
db.session.commit()#增

user=User.query.filter(User.username=='mis0106').first()
print(user.username,user.password)
db.session.commit()#查

user=User.query.filter(User.username=='mis0106').first()
user.password='654321'
db.session.commit()#改

user=User.query.filter(User.username=='mis0106').first()
db.session.delete(user)
db.session.commit()#删

@app.route('/')
def index():
    return render_template('index.html')


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

config.py

SQLALCHEMY_DATABASE_URI = 'mysql+pymysql://root:@127.0.0.1:3306/mis_db?charset=utf8'
SQLALCHEMY_TRACK_MODIFICATIONS = False