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()

config.py:

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

增删改查：

from flask import Flask
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=TabError,autoincrement=True)
    username = db.Column(db.String(20),nullable=False)
    password = db.Column(db.String(20), nullable=False)

#db.create_all()

#增加
user = User(username='123456',password = '456789')
db.session.add(user)
db.session.commit()

#查询
user =User.query.filter(User.username =='abcdef').first()
print(user.username,user.password)

#修改
user =User.query.filter(User.username =='123456').first()
user.password='abcdef'
print(user.username,user.password)
db.session.commit()

#删除
user =User.query.filter(User.username =='123456').first()
print(user.username,user.password)
db.session.delete(user)
db.session.commit()

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


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

增加：    

查询：

修改：

删除：